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Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 6, Nuclear Physics, tamilnadu board, Physics,

Question 1.
Identify A, B, C, and D from the following nuclear reactions.

Solution:


Samacheer Kalvi 10th Science Solutions Chapter 6 Nuclear Physics 2

A is alpha particle, B is neutron, C is proton and D is electron.

Question 2.
A radon specimen emits radiation of 3.7 × 103 GBq per second. Convert this disintegration in terms of a curie, (one curie = 3.7 × 1010 disintegration per second)
Solution:
1 Bq = one disintegration per second
one curie = 3.7 × 1010 Bq

Question 3.
92U235 experiences one α – decay and one β – decay. Find the number of neutrons in the final daughter nucleus that is formed.
Solution:
Let X and Y be the resulting nucleus after the emission of the alpha and beta particles respectively.

Number of neutrons = Mass number – Atomic number = 231 – 91 = 140.

Question 4.
Calculate, the amount of energy released when a radioactive substance undergoes fusion and results in a mass defect of 2 kg.
Solution:
Mass defect in the reaction (m) = 2 kg
Velocity of light (c) = 3 × 108 ms-1
By Einstein’s equation,
Energy released E = mc2
= 2 × (3 × 108)2
= 1.8 × 1017 J.

Samacheer Kalvi 10th Science Nuclear Physics Textual Evaluation

I. Choose the correct answer

Question 1.
Man – made radioactivity is also known as _____.
(a) Induced radioactivity
(b) Spontaneous radioactivity
(c) Artificial radioactivity
(d) (a) & (c).
Answer:
(d) (a) & (c).

Question 2.
Unit of radioactivity is:
(a) roentgen
(b) curie
(c) becquerel
(d) all the above
Answer:
(d) all the above

Question 3.
Artificial radioactivity was discovered by _____.
(a) Becquerel
(b) Irene Curie
(c) Roentgen
(d) Neils Bohr.
Answer:
(b) Irene Curie

Question 4.
In which of the following, no change in mass number of the daughter nuclei takes place:
(i) a decay;
(ii) P decay
(iii) y decay
(iv) neutron decay
(a) (i) is correct
(b) (ii) and (iii) are correct
(c) (i) and (iv) are correct
(d) (ii) and (iv) are correct
Answer:
(b) (ii) and (iii) are correct

Question 5.
_____ isotope is used for the treatment of cancer.
(a) Radio Iodine
(b) Radio Cobalt
(c) Radio Carbon
(d) Radio Nickel.
Answer:
(b) Radio Cobalt

Question 6.
Gamma radiations are dangerous because:
(a) it affects eyes and bones
(b) it affects tissues
(c) it produces genetic disorder
(d) it produces an enormous amount of heat
Answer:
(c) it produces genetic disorder

Question 7.
_____ aprons are used to protect us from gamma radiations.
(a) Lead oxide
(b) Iron
(c) Lead
(d) Aluminium.
Answer:
(c) Lead

Question 8.
Which of the following statements is / are correct?
(i) α particles are photons
(ii) Penetrating power of γ radiation is very low
(iii) Ionization power is maximum for α rays
(iv) Penetrating power of γ radiation is very high
(a) (i) & (ii) are correct
(b) (ii) & (iii) are correct
(c) (iv) only correct
(d) (iii) & (iv) are correct.
Answer:
(d) (iii) & (iv) are correct.

Question 9.
Proton-Proton chain reaction is an example of:
(a) Nuclear fission
(b) α – decay
(c) Nuclear fusion
(d) β – decay
Answer:
(c) Nuclear fusion

Question 10.
In the nuclear reaction X126⟶α decay zYA, the value of A & Z.
(a) 8, 6
(b) 8, 4
(c) 4, 8
(d) cannot be determined with the given data.
Answer:
(c) 4, 8

Question 11.
Kamini reactor is located at _____.
(a) Kalpakkam
(b) Koodankulam
(c) Mumbai
(d) Rajasthan.
Answer:
(a) Kalpakkam

Question 12.
Which of the following is/are correct?
(i) Chain reaction takes place in a nuclear reactor and an atomic bomb.
(ii) The chain reaction in a nuclear reactor is controlled.
(iii) The chain reaction in a nuclear reactor is not controlled.
(iv) No chain reaction takes place in an atom bomb.
(a) (i) only correct
(b) (i) & (ii) are correct
(c) (iv) only correct
(d) (iii) & (iv) are correct
Answer:
(b) (i) & (ii) are correct

II. Fill in the blanks

Question 1.
One roentgen is equal to ______ disintegrations per second?
Answer:
3.7 × 1010.

Question 2.
Positron is an _____.
Answer:
antiparticle of electron.

Question 3.
Anaemia can be cured by _____ isotope.
Answer:
Radio iron (Fe59).

Question 4.
Abbreviation of ICRP _____.
Answer:
International Commission on Radiological Protection.

Question 5.
_____ is used to measure the exposure rate of radiation in humans.
Answer:
Roentgen.

Question 6.
_____ has the greatest penetration power.
Answer:
Gamma ray.

Question 7.
zYA→Z+1YA+X; Then X is _____.
Answer:
−1e0 (β decay).

Question 8.
zXA→YAZ This reaction is possible in _____ decay.
Answer:
Gamma (γ).

Question 9.
The average energy released in each fusion reaction is about _____ J.
Answer:
3.84 × 10-12.

Question 10.
Nuclear fusion is possible only at an extremely high temperature of the order of _____ K.
Answer:
107 to 109.

Question 11.
The radioisotope of _____ helps to increase the productivity of crops.
Answer:
phosphorous (P – 32).

Question 12.
If radiation exposure is 100 R, it may cause _____.
Answer:
fatal disease.

III. State whether the following statements are true or false: If false, correct the statement

Question 1.
Plutonium -239 is a fissionable material.
Answer:
True.

Question 2.
Elements having an atomic number greater than 83 can undergo nuclear fusion.
Answer:
False.
Correct Statement: Elements having an atomic number greater than 83 can undergo nuclear fusion.

Question 3.
Nuclear fusion is more dangerous than nuclear fission.
Answer:
False.
Correct Statement: Nuclear fission is more dangerous than nuclear fusion. Because the average energy released in fission (3.2 × 10-11 J) process is more than the average energy released in fusion (3.84 × 10-12 J).

Question 4.
Natural uranium U-238 is the core fuel used in a nuclear reactor.
Answer:
False.
Correct Statement: U-238 is not a fissile material but are abundant in nature. But in a reactor, this can be converted into a fissile material Pu239 and U233. Only fissile materials are used in the fuel of a nuclear reactor.

Question 5.
If a moderator is not present, then a nuclear reactor will behave like an atom bomb.
Answer:
True.

Question 6.
During one nuclear fission on an average, 2 to 3 neutrons are produced.
Answer:
True.

Question 7.
Einstein’s theory of mass-energy equivalence is used in nuclear fission and fusion.
Answer:
True.

IV. Match the following

Question 1.

1. BARC(a) Kalpakkam
2. India’s first atomic power station(b) Apsara
3. IGCAR(c) Mumbai
4. The first nuclear reactor in India(d) Tarapur

Answer:
1. (c) Mumbai
2. (d) Tarapur
3. (a) Kalpakkam
4. (b) Apsara

Question 2.

1. Fuel(a) lead
2. Moderator(b) heavy water
3. Coolant(c) Graphite
4. Shield(d) Uranium

Answer:
1. (d) uranium
2. (c) Graphite
3. (b) heavy water
4. (a) lead

Question 3.

1. Soddy Fagan(a) Natural radioactivity
2. Irene Curie(b) Displacement law
3. Henry Becquerel(c) Mass energy equivalence
4. Albert Einstein(d) Artificial Radioactivity

Answer:
1. (b) Displacement law
2. (d) Artificial Radioactivity
3. (a) Natural radioactivity
4. (c) Mass energy equivalence

Question 4.

1. Uncontrolled fission Reaction(a) Hydrogen Bomb
2. Fertile material(b) Nuclear Reactor
3. Controlled fission Reaction(c) Breeder reactor
4. Fusion reaction(d) Atom bomb

Answer:
1. (d) Atom bomb
2. (c) Breeder reactor
3. (b) Nuclear Reactor
4. (a) Hydrogen Bomb

Question 5.

1. Co – 60(a) Age of fossil
2. I – 13(b) Function of Heart
3. Na – 24(c) Leukaemia
4. C – 14(d) Thyroid disease

Answer:
1. (c) Leukemia
2. (d) Thyroid disease
3. (b) Function of Heart
4. (a) Age of fossil

V. Arrange the following in the correct sequence

Question 1.
Arrange in descending order, on the basis of their penetration power.

  1. Alpha rays
  2. Beta rays
  3. Gamma rays
  4. Cosmic rays.

Answer:

  1. Gamma rays
  2. Beta rays
  3. Alpha rays
  4. Cosmic rays.

Question 2.
Arrange the following in the chronological order of discovery.

  1. A nuclear reactor
  2. Radioactivity
  3. Artificial radioactivity
  4. Discovery of radium.

Answer:

  1. Radioactivity (1896)
  2. Discovery of radium (1898)
  3. Artificial radioactivity (1934)
  4. Nuclear reactor (1942).

VI. Use the analogy to fill in the blank

Question 1.
Spontaneous process : Natural Radioactivity, Induced process: _____.
Answer:
Artificial radioactivity
(or)
Man – made activity.

Question 2.
Nuclear Fusion : Extreme temperature, Nuclear Fission: _____.
Answer:
Room temperature.

Question 3.
Increasing crops : Radio phosphorous, Effective functioning of heart: _____.
Answer:
Radio sodium (Na24).

Question 4.
Deflected by electric field : α ray, Null Deflection: _____.
Answer:
γ ray (Gamma – ray).

VII. Numerical Problems

Question 1.
88Ra226 experiences three α-decay. Find the number of neutrons in the daughter element.
Solution:
88Ra226 consider as a parent element that is 88X226 and their daughter element is zYA
According to α decay process,
88X26⟶3α decay 82214+3α decay
During the 3α decay, the atomic number decreases by 6 and mass number decreases by 12.
So the number of neutrons in the daughter element
N = A – Z
N = 214 – 88 = 126
Number of neutrons in the daughter element N = 126.

Question 2.
A cobalt specimen emits induced radiation of 75.6 millicurie per second. Convert this disintegration in to becquerel (one curie = 3.7 × 1010 Bq).
Solution:
Cobalt specimen emits induced radiation = 75.6 millicurie per second
(1 curie = 3.7 × 1010 Bq)
So 75.6 millicurie = 75.6 × 103 × 1 curie
= 75.6 × 10-3 × 3.7 × 1010 Bq
= 279.72 × 107
= 2.7972 × 109 Bq
75.6 millicurie per second is equivalent to 2.7972 × 109 Bq.

VIII. Assertion and Reason Type Questions

Mark the correct choice as
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.

Question 1.
Assertion: A neutron impinging on U235, splits it to produce Barium and Krypton.
Reason: U-235 is a fissile material.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.

Question 2.
Assertion: In a β – decay, the neutron number decreases by one.
Reason: In β – decay atomic number increases by one.
Answer:
(d) The assertion is false, but the reason is true.
Explanation: In β – decay there is no change in the mass number of the daughter nucleus but the atomic number increases by one.

Question 3.
Assertion: Extreme temperature is necessary to execute nuclear fusion.
Reason: In nuclear fusion, the nuclei of the reactants combine releasing high energy.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.

Question 4.
Assertion: Control rods are known as ‘Neutron seeking rods’
Reason: Control rods are used to perform a sustained nuclear fission reaction.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
Explanation: Control rods are used to control the number of neutrons in order to have a sustained the chain reaction. They absorb the neutrons, (they seeking the neutrons)

IX. Answer in one or two words (VSA)

Question 1.
Who discovered natural radioactivity?
Answer:
Henri Becquerel was discovered natural radioactivity.

Question 2.
Which radioactive material is present in the ore of pitchblende?
Answer:
Uranium

Question 3.
Write any two elements which are used for inducing radioactivity?
Answer:

  1. Boron and Aluminium.
  2. Alpha particle and neutron.

Question 4.
Write the name of the electromagnetic radiation which is emitted during a natural radioactivity.
Answer:
Gamma rays

Question 5.
If A is a radioactive element which emits an α-particle and produces 104Rf259. Write the atomic number and mass number of the element A.
Answer:
In α decay
zXAα decay 263×z−2YA−4+2He4(α decay )106X263⟶α decay 104Rf259+2He4
In element A having atomic number is 106 and mass number is 263.

Question 6.
What is the average energy released from a single fission process?
Answer:
The average energy released from a single fission process is about 3.2 × 10-11 J.

Question 7.
Which hazardous radiation is the cause for the genetic disorders (or) effect?
Answer:
Radioactive radiations

Question 8.
What is the amount of radiation that may cause the death of a person when exposed to it?
Answer:
When the body is exposed to about 600 R, it leads to death.

Question 9.
When and where was the first nuclear reactor built?
Answer:
The first nuclear reactor was built in 1942 in Chicago, USA.

Question 10.
Give the SI unit of radioactivity.
Answer:
Becquerel

Question 11.
Which material protects us from radiation?
Answer:
Lead coated aprons and lead gloves should be used while working with the hazardous area. These materials are used to protects us from radiation.

X. Answer the following questions in a few sentences.

Question 1.
Write any three features of natural and artificial radioactivity.
Answer:

Natural radioactivityArtificial radioactivity
1. Emission of radiation due to the self-disintegration of a nucleus.1. Emission of radiation due to the disintegration of a nucleus through the induced process.
2. Alpha, Beta and Gamma radiations are emitted.2. Mostly elementary particles such as neutron, positron, etc. are emitted.
3. It is a spontaneous process.3. It is an induced process.

Question 2.
Define critical mass.
Answer:
The minimum mass of fissile material necessary to sustain the chain reaction is called ‘critical mass (mc). It depends on the nature, density and the size of the fissile material.

Question 3.
Define One roentgen.
Answer:
One roentgen is defined as the quantity of radioactive substance which produces a charge of 2.58 × 10-4 coulomb in 1 kg of air under standard conditions of pressure, temperature and humidity.

Question 4.
State Soddy and Fagan’s displacement law.
Answer:
During a radioactive disintegration, the nucleus which undergoes disintegration is called a parent nucleus and that which remains after the disintegration is called the daughter nucleus.

Question 5.
Give the function of control rods in a nuclear reactor.
Answer:
Control rods are used to control the number of neutrons in order to have sustained chain reaction. Mostly boron or cadmium rods are used as control rods. They absorb the neutrons.

Question 6.
In Japan, some of the newborn children are having congenital diseases. Why?
Answer:
During the Second World War American, a bomber dropped the nuclear weapons over the Japanese cities of Hiroshima and Nagasaki. In the explosion of the atomic bomb to release the high energy dangerous radiation. In the explosion period, Japanese peoples are affected by radiation. This is the reason in Japan, some of the newborn children are having congenital diseases.

Question 7.
Mr Ramu is working as an X – ray technician in a hospital. But, he does not Wear the lead aprons. What suggestion will you give to Mr Ramu?
Answer:
X – rays have a destructive effect on living tissue. When the human body is exposed to X – rays, it causes redness of the skin, sores and serious injuries to the tissues and glands. They destroy the white corpuscles of the blood. If you don’t wear the lead aprons these kinds of diseases formed in your body. In my suggestion, you must wear lead aprons.

Question 8.
What is stellar energy?
Answer:
Fusion reaction that takes place in the cores of the Sun and other stars results in an enormous amount of energy, which is called as stellar energy.

Question 9.
Give any two uses of radioisotopes in the field of agriculture?
Answer:

  • The radioisotope of phosphorus (P – 32) helps to increase the productivity of crops.
  • The radiations from the radioisotopes can be used to kill the insects and parasites and prevent the wastage of agricultural products.

XI. Answer the following questions in detail.

Question 1.
Explain the process of controlled and uncontrolled chain reactions.
Answer:
(a) Controlled chain reaction

  • In the controlled chain reaction, the number of neutrons released is maintained to be one. This is achieved by absorbing the extra neutrons with a neutron absorber leaving only one neutron to produce further fission.
  • Thus, the reaction is sustained in a controlled manner. The energy released due to a controlled chain reaction can be utilized for constructive purposes.
  • The controlled chain reaction is used in a nuclear reactor to produce energy in a sustained and controlled manner.

(b) Uncontrolled chain reaction:

Question 2.
Compare the properties of Alpha, Beta and Gamma radiations.
Answer:

Propertiesα raysβ raysγ rays
What are they?Helium nucleus (2He4)consisting of two protons and two neutrons.They are electrons (−1e0), basic elementary particle in all atoms.They are electromagnetic waves consisting of photons.
ChargePositively charged particles. Charge of each alpha particle = +2eNegatively charged particles. Charge of each beta particle = -eNeutral particles. Charge of each gamma particle = zero
Ionising Power100 time greater than β rays and 10,000 times greater than γ raysComparatively lowVery less ionization power
Penetrating powerLow penetrating power (even stopped by a thick paper)Penetrating power is greater than that of α rays. They can penetrate through a thin metal foil.They have a very high penetrating power greater than that of β rays. They can penetrate through thick metal blocks.
Effect of an electric and magnetic fieldDeflected by both the fields. (in accordance with Fleming’s left-hand rule)Deflected by both the fields, but the direction of deflection is opposite to that for alpha rays. (in accordance with Fleming’s left-hand rule)They are not deflected by both the fields.
SpeedTheir speed ranges from 1/10 to 1/20 times the speed of light.Their speed can go up to 9/10 times the speed of light.They travel with the speed of light.

Question 3.
What is a nuclear reactor? Explain its essential parts with their functions.
Answer:
Nuclear reactor: A Nuclear reactor is a device in which the nuclear fission reaction takes place in a self – sustained and controlled manner to produce electricity.

Components of a Nuclear Reactor:
The essential components of a nuclear reactor are

  • Fuel: A fissile material is used as the fuel. The commonly used fuel material is uranium.
  • Moderator: A moderator is used to slow down the high energy neutrons to provide slow neutrons. Graphite and heavy water are commonly used moderators.
  • Control rod: Control rods are used to control the number of neutrons in order to have a sustained a chain reaction. Mostly boron or cadmium rods are used as control rods. They absorb the neutrons.
  • Coolant: A coolant is used to remove the heat produced in the reactor core, to produce steam. This steam is used to run a turbine in order to produce electricity. Water, air and helium are some of the coolants.
  • Protection wall: A thick concrete lead wall is built around the nuclear reactor in order to prevent the harmful radiations from escaping into the environment.

XII. HOT Questions

Question 1.
Mass number of a radioactive element is 232 and its atomic number is 90. When this element undergoes certain nuclear reactions, it transforms into an isotope of lead with a mass number 208 and an atomic number 82. Determine the number of alpha and beta decay that can occur.
Answer:
Mass number A = 232
Atomic number Z = 90
Daughter element:
Mass number A = 208
Atomic number Z = 82
Difference in mass number = 232 – 208 = 24
Difference in atomic number
= 90 – 82 = 8
Atomic number of α = 2
Atomic number of β = -1
Mass number of α = 4
Mass number of β = 0
Difference in mass number in transformations
= 24
Number of a decays = 244 = 6
Difference in atomic number = 8
ΔZ = 6α + 4β
= 6(2) + 4(-1)
= 12 – 4
= 8
∴ Number of β decays = 4
∴ Number of α decays = 6
∴ Number of β decays = 4

Question 2.
‘X – rays should not be taken often’. Give the reason.
Answer:

  • Radiation does involve in X – rays tests and isotope scans (in nuclear medicine) are too low to cause immediate hazardous effects.
  • If should be taken often, X – ray radiation from medical examinations though slightly increases one’s risk for cancer which can occur year or decades after X-ray exposure.

Question 3.
Cell phone towers should be placed far away from the residential area. why?
Answer:

  1. Living near a cell phone tower is not healthy. There is multiple health risks associated with living near a cell phone tower.
  2. Cell phone towers communicate by use pulsed microwave signals (radiofrequency radiation) with each other.
  3. That is the reason cell phone towers should be placed far away from the residential area.

Samacheer Kalvi 10th Science Nuclear Physics Additional Questions

I. Choose the best Answer.

Question 1.
Radium was discovered by _____.
(a) Marie curie
(b) Irene curie
(c) Henri Becquerel
(d) F. Joliot.
Answer:
(a) Marie Curie

Question 2.
How many radioactive substances discovered so far?
(a) 83
(b) 92
(c) 43
(d) 29
Answer:
(d) 29

Question 3.
The SI unit of Radioactivity is _____.
(a) Curie
(b) Rutherford
(c) Becquerel
(d) Roentgen (R).
Answer:
(c) Becquerel

Question 4.
Radioactivity is _____.
(a) increases with increase in temperature
(b) increases with increase in pressure
(c) depends on the number of electrons
(d) purely a nuclear phenomenon.
Answer:
(d) purely a nuclear phenomenon

Question 5.
Which of the following processes is a spontaneous process?
(a) Artifical radioactivity
(b) Natural radioactivity
(c) Photoelectric effect
(d) Collisions
Answer:
(b) Natural radioactivity

Question 6.
The charge of the β rays _____.
(a) 2e
(b) 0
(c) -e
(d) none of these.
Answer:
(c) -e

Question 7.
The charge of the γ rays _____.
(a) 2e
(b) 0
(c) -e
(d) none of these.
Answer:
(b) 0

Question 8.
The atomic number of the elements that exhibit artifical radioactivity is:
(a) more than 82
(b) more than 83
(c) less than 83
(d) less than 82
Answer:
(c) less than 83

Question 9.
Arrange α, β, γ rays in the increasing order of their ionizing power.
(a) α, β, γ
(b) β, α, γ
(c) γ, β, α
(d) γ, α, β.
Answer:
(c) γ, β, α

Question 10.
Which produces a charge of 2.58 × 10-4Coulomb in 1 Kg of air?
(a) Curie
(b) Becquerel
(c) Rutherford
(d) Roentgen
Answer:
(d) Roentgen

Question 11.
Ionising power of the γ rays _____.
(a) Comparatively very high ionization power
(b) 100 times greater than the α rays
(c) 100 times greater than the β rays
(d) Comparatively very less ionization power.
Answer:
(d) Comparatively very less ionization power.

Question 12.
Ionization power maximum for _____.
(a) neutrons
(b) α particles
(c) γ rays
(d) β particles.
Answer:
(b) α particles

Question 13.
Charge of gamma particle is:
(a) +2e
(b) -e
(c) Zero
(d) +1e
Answer:
(c) Zero

Question 14.
Which has low penetrating power?
(a) α rays
(b) γ rays
(c) β rays
(d) X rays.
Answer:
(a) α rays

Question 15.
In β – decay _____.
(a) atomic number decreases by one
(b) the mass number decreases by one
(c) proton number remains the same
(d) neutron number decreases by one.
Answer:
(d) neutron number decreases by one

Question 16.
In which decay the energy level of the nucleus changes:
(a) α – decay
(b) β – decay
(c) γ – decay
(d) neutron decay
Answer:
(c) γ – decay

Question 17.
In γ – decay _____.
(a) atomic number decreases by one
(b) there is no change in atomic and mass number
(c) energy only changes in the decay process
(d) both (b) and (c).
Answer:
(d) both (b) and (c).

Question 18.
The unit of decay constant is _____.
(a) no unit
(b) second
(c) second-1
(d) curie.
Answer:
(c) second-1

Question 19.
The range of temperature required for nuclear fusion is from:
(a) 107 to 109 K
(b) 10-9 to 10-7 K
(c) 105 to 109
(d) 105 to 107 K
Answer:
(a) 107 to 109 K

Question 20.
1 Rd is equal to _____.
(a) 106 decay / second
(b) 1 decay / second
(c) 3.7 × 1010 becquerel
(d) 1.6 × 1012 decay / second.
Answer:
(a) 106 decay / second

Question 21.
An element ZXA successively undergoes three α decays and four β decays and gets converted an element Y are respectively _____.
(a) Z−6YA−12
(b) Z+2YA−12
(c) Z−2YA−12
(d) Z−10YA−12.
Answer:
(c) Z−2YA−12

Question 22.
In the nuclear reaction 88Ra226 → X + 2He4X is:
(a) 90Th234
(b) 91Pa234
(c) 86Rn222
(d) 88Rn226
Answer:
(d) 88Rn226

Question 23.
Which one of the following is used in the treatment of skin diseases _____.
(a) Na24
(b) I31
(c) Fe59
(d) P32.
Answer:
(d) P32.

Question 24.
Anaemia can be diagnosed by _____.
(a) 15P31
(b) 15P32
(c) 26P59
(d) 11P24.
Answer:
(c) 26P59

Question 25.
Which is used as a coolant?
(a) Graphite
(b) Liquid sodium
(c) Boron
(d) Cadmium
Answer:
(b) Liquid sodium

Question 26.
The energy released per fission is _____.
(a) 220 MeV
(b) 300 MeV
(c) 250 MeV
(d) 200 MeV.
Answer:
(d) 200 MeV.

Question 27.
In the reaction 1N14 + 0n1 → X + 1H1 X is:
(a) 15P30
(b) 6C14
(c) 6C12
(d) 11Na23
Answer:
(c) 6C12

Question 28.
Natural uranium consists of _____.
(a) 99.72 % of U-238
(b) 0.28 % of U-238
(c) 0.72 % of U-238
(d) 99.28 % of U-238.
Answer:
(d) 99.28 % of U-238.

Question 29.
The number of power reactors in India is _____.
(a) 14
(b) 12
(c) 7
(d) 2.
Answer:
(a) 14

Question 30.
In the nucleus of 11Na23 the number of protons and neutrons are:
(a) 12, 11
(b) 10, 12
(c) 11, 12
(d) 11, 23
Answer:
(c) 11, 12

Question 31.
The moderator used in nuclear reactor is _____.
(a) cadmium
(b) boron carbide
(c) heavy water
(d) uranium (92U235).
Answer:
(c) heavy water

Question 32.
The first nuclear reactor was built at _____.
(a) Kalpakkam, India
(b) Hiroshima, Japan
(c) Chicago, USA
(d) Trombay, Bombay.
Answer:
(c) Chicago, USA

Question 33.
Which of the following is used in the treatment of skin cancer?
(a) Radio Cobalt
(b) Radio gold
(c) Radio Cobalt and radio gold
(d) none of the above
Answer:
(c) Radio Cobalt and radio gold

Question 34.
The explosion of an atom bomb is based on the principle of _____.
(a) uncontrolled fission reaction
(b) fusion reaction
(c) controlled fission reaction
(d) none of the above.
Answer:
(a) uncontrolled fission reaction

Question 35.
The reactor in which no moderator used is _____.
(a) fast breeder reactor
(b) pressurised water reactor
(c) pressurised heavy water reactor
(d) boiled water reactor.
Answer:
(a) fast breeder reactor

Question 36.
The number of neutrons present in 92U235is:
(a) 133
(b) 143
(c) 43
(d) 243
Answer:
(b) 143

Question 37.
In fast breeder, the coolant system used is _____.
(a) heavy water
(b) light water
(c) liquid sodium
(d) boiled water.
Answer:
(c) liquid sodium

Question 38.
The only reactor in the world which uses U-233 as fuel is _____.
(a) Zerlina
(b) Purnima
(c) Kamini
(d) Tires.
Answer:
(c) Kamini

Question 39.
The temperature of the interior of Sun is about _____.
(a) 1.4 × 107 K
(b) 108 K
(C) 14 × 107 K
(d) 600 K.
Answer:
(a) 1.4 × 107 K

Question 40.
Total energy radiated by Sun is about _____.
(a) 3.6 × 1028 Js-1
(b) 3.8 × 1028 Js-1
(c) 3.8 × 1026 Js-1
(d) 3.8 × 1023 Js-1.
Answer:
(c) 3.8 × 1026 Js-1


II. Fill in the blanks

Question 1.
Cathode rays are discovered by _____.
Answer:
J.J. Thomson.

Question 2.
Positive rays discovered by _____.
Answer:
Goldstein.

Question 3.
The chargeless particles are called neutron, it was discovered by _____.
Answer:
James Chadwick.

Question 4.
Ernest Rutherford explained that the mass of an atom is concentrated in its central part called _____.
Answer:
Nucleus.

Question 5.
The radioactive elements emit harmful radiations are ____, ____, ____ rays.
Answer:
alpha, beta, gamma.

Question 6.
_____ is an spontaneous process.
Answer:
Natural radioactivity.

Question 7.
The element whose atomic number is more than 83 undergoes _____.
Answer:
spontaneous process.

Question 8.
______ radioactive material is present in the ore of pitchblende.
Answer:
Uranium.

Question 9.
_____ are the example of artificial (or) man-made radioactive elements.
Answer:
Boron, Aluminium.

Question 10.
The element whose atomic number is less than 83 undergoes _____.
Answer:
induced radioactivity.

Question 11.
______ is an controlled manner.
Answer:
Artificial radioactivity.

Question 12.
Spontaneous radioactivity is also known as _____.
Answer:
Natural radioactivity.

Question 13.
One Curie is equal to _____ disintegrations per second.
Answer:
3.7 × 1010

Question 14.
One Rutherford (Rd) is equal to ______ disintegrations per second.
Answer:
106

Question 15.
The radioactive displacement law is framed by _____.
Answer:
Soddy and Fajan.

Question 16.
During the α decay process, the atomic number is ______ by 2 and the mass number is decreases by _____.
Answer:
decreases, 4.

Question 17.
In β-decay the atomic number increases by ____ unit and mass number _____.
Answer:
One, remains the same.

Question 18.
In α radiation, the charge of each alpha particle is _____.
Answer:
+2e.

Question 19.
In γ radiation, the charge of each gamma particle is _____.
Answer:
Zero.

Question 20.
In radioactive radiation, which one is travel with the speed of light _____.
Answer:
Gamma radiation.

Question 21.
zYA→z−2YA−4+X; Then X is _____.
Answer:
2He4 (α decay).

Question 22.
zYA→zYA+X; Then X is _____.
Answer:
γ decay.

Question 23.
The average energy released in each fission process in about _____.
Answer:
3.2 × 10-11 J.

Question 24.
Fissionable material is a radioactive element, which undergoes fission in a sustained manner when it absorbs a _____.
Answer:
Neutron.

Question 25.
_____ isotope is used to detect the presence of block in blood vessels and also used for the effective functioning of the heart.
Answer:
Na24 – Radio sodium.

Question 26.
_____ is used to cure goitre.
Answer:
Radio Iodine – I131

Question 27.
_____ is used to diagnose anaemia and also to provide treatment for the same.
Answer:
Radio – iron (Fe59).

Question 28.
Radio cobalt (Co60) and radio gold (Au198) are used in the treatment of _____.
Answer:
Skin cancer.

Question 29.
_____ are used to sterilize the surgical devices as they can kill the germs and microbes.
Answer:
Radiations.

Question 30.
The age of the earth, fossils, old paintings and monuments can be determined by _____. technique.
Answer:
Radiocarbon dating.

Question 31.
When the body is exposed to about 600 R, it leads to _____.
Answer:
Death.

Question 32.
Radioactive materials should be kept in a thick – walled container of _____.
Answer:
Lead.

Question 33.
_____ is used to remove the heat produced in the reactor core, to produce steam.
Answer:
Coolant.

Question 34.
The abbreviation of BARC is _____.
Answer:
Bhabha Atomic Research Centre.

Question 35.
India’s 1st nuclear power station is _____.
Answer:
Tarapur Atomic Power Station.

Question 36.
The first nuclear reactor built in India was _____.
Answer:
Apsara.

Question 37.
The total nuclear power operating sites in India is _____.
Answer:
7

Question 38.
The energy released in a nuclear fission process is about ______
Answer:
200 Mev.

Question 39.
The number of 0n1 released on an average per fission is _____.
Answer:
2.5.

Question 40.
A hydrogen bomb is based on the principle of _____.
Answer:
Nuclear fusion.

III. Match the following

Question 1.

1. Natural radioactivity(a) 3.7 × 1010decay/second
2. Artificial radioactivity(b) spontaneous process
3. 1 curie(c) 106decay/second
4. 1 Rd (Rutherford)(d) induced process

Answer:
1. (b) spontaneous process
2. (d) induced process
3. (a) 3.7 × 1010 decay / second
4. (c) 106 decay / second

Question 2.

1. Charge of each α particle(a) γ ray
2. Charge of each β particle(b) +2e
3. Penetration power is maximum(c) α ray
4. Ionisation power is maximum(d) zero

Answer:
1. (b) +2e
2. (d) zero
3. (a) γ ray
4. (e) α ray

Question 3.

1. Deuterium(a) −1e0
2. Protium(b) 1H3
3. Tritium(c) 2H4
4. α – decay(d) 1H1
5. β – decay(e) 1H2

Answer:
1. (e) 1H2
2. (d) 1H1
3. (b) 1H3
4. (c) 2H4
5. (a) −1e0

Question 4.

1. Uranium core bomb(a) fusion bomb
2. Plutonium core bomb(b) fission bomb
3. Hydrogen bomb(c) Nagasaki
4. Atom bomb(d) Hiroshima

Answer:
1. (d) Hiroshima
2. (c) Nagasaki
3. (a) fusion bomb
4. (b) fission bomb

Question 5.

1. Radio iron (Fe59)(a) treatment of skin diseases
2. Radio phosphorous (P32)(b) smoke detector
3. Radio gold (Au198)(c) diagnose anaemia
4. An isotope of Americium (Am241)(d) treatment of skin cancer

Answer:
1. (c) diagnose anaemia
2. (a) treatment of skin diseases
3. (d) treatment of skin cancer
4. (b) smoke detector

IV. Arrange the following in the correct sequence

Question 1.
Arrange α, β, γ rays in ascending order, on the basis of their penetrating power?
Answer:
Ascending order:

  • Alpha (α)
  • Beta (β)
  • Gamma (γ)

Question 2.
Arrange in ascending and descending order, on the basis of their Ionisation power.
Alpha (α), Beta (β), Gamma (γ)
Answer:

  1. Ascending order: Gamma (γ), Beta (β), Alpha (α)
  2. Descending order: Alpha (α), Beta (β), Gamma (γ)

Question 3.
Arrange in ascending and descending order, on the basis of their biological effect.
Alpha (α), Gamma (γ), Beta (β)
Answer:

  1. Ascending order: Alpha (α), Beta (β), Gamma (γ)
  2. Descending order: Gamma (γ), Beta (β), Alpha (α).

V. Numerical Problems

Question 1.
92U238 emits 8α particles and 6β particles. What is the neutron / proton ratio in the product nucleus?
Solution:

Question 2.
The element with atomic number 84 and mass number 218 change to another element with atomic number 84 and mass number 214. The number of α and β particles emitted are respectively?
Solution:
Samacheer Kalvi 10th Science Solutions Chapter 6 Nuclear Physics 8
Number of alpha decay, x = 1
Number of beta decay, y = 2.

Question 3.
The number of α and β particles emitted in the nuclear reaction 90Th228⟶83Bi12are respectively.
Solution:
Samacheer Kalvi 10th Science Solutions Chapter 6 Nuclear Physics 9
Number of α decay, x = 4
Number of β decay, y = 1.

VI. Assertion and Reason Type Questions

(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
(c) If Assertion is true, but the reason is false.
(d) If Assertion is false, but the reason is true.
(e) If the Assertion and reason both are false.

Question 1.
Assertion: All the radioactive element are ultimately converted in lead.
Reason: All the elements above lead are unstable.
Answer:
(c) If Assertion is true, but the reason is false.
Explanation: When they are converted into a lead, the emission is stopped because the nucleus of lead is stable (or lead is most stable elements in radioactive series)

Question 2.
Assertion: Among the alpha, beta and gamma-ray a particle has maximum penetrating power.
Reason: The alpha particle is heavier than beta and gamma rays.
Answer:
(e) If the Assertion and reason both are false.
Explanation: The penetrating power is maximum in case of gamma rays because gamma rays are electromagnetic radiation of very small wavelength.

Question 3.
Assertion: The ionising power of β – particle is less compared to α – particles but their penetrating power is more.
Reason: The mass of β-particle is less than the mass of α-particle
Answer:
(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
Explanation: β – particle being emitted with very high speed compared to α – particle. Due to this reason, their loss of energy is very slow and they can penetrate the medium through a sufficient depth.

Question 4.
Assertion: Neutrons penetrate matter more readily as compared to protons.
Reason: Neutrons are slightly more massive than protons.
Answer:
(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
Explanation: Neutron is about 0.1 % more massive than a proton. But the unique thing about the neutron is that while it is heavy, it has no charge (it is neutral). This lack of charge gives it the ability to penetrate matter without interacting as quickly as the beta particles or alpha particles.

Question 5.
Assertion: zXA undergoes a decays and the daughter product is z−2YA−4
Reason: In α – decay, the mass number decreases by 4 and atomic number decreases by.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
Explanation: zXA⟶z−2XA−4+2He4(α decay)

Question 6.
Assertion: Moderator is used to slowing down the high energy neutrons to provide slow neutrons.
Reason: Cadmium rods are used as control rods.
Answer:
(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
Explanation: Graphites and heavy water are commonly used moderators. This helps in moderator to slow down the fast neutrons.

Question 7.
Assertion: Alpha, beta and gamma radiations are emitted.
Reason: Nuclear fission process can be performed at room temperature.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
Explanation: At room temperature, the nuclear fission process can perform breaking up of heavier nucleus into two smaller nuclei. In this process to emitted the alpha, beta and gamma radiations.

Question 8.
Assertion: An enormous amount of energy is released which is called stellar energy.
Reason: Fusion reaction that takes place in the cores of the Sun and other stars.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
Explanation: The stars like our Sun emit a large amount of energy in the form of light and heat. This energy is termed as the stellar energy.

Question 9.
Assertion: Artificial radioactivity is a controlled process.
Reason: It is a spontaneous process – natural radioactivity.
Answer:
(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
Explanation: Artificial radioactivity is a controlled process. It is an induced process and man-made radioactivity.

Question 10.
Assertion: Gamma rays, penetrates through materials most effectively.
Reason: Gamma rays, which have the shortest wavelengths of all electromagnetic radiation.
Answer:
(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
Explanation: Gamma rays, which have the shortest wavelengths of all electromagnetic radiation. This is a reason they can penetrate through materials most effectively.

VII. Answer the following questions

Question 1.
Define ‘Radioactivity’.
Answer:
The phenomenon of nuclear decay of certain elements with the emission of radiations like alpha, beta, and gamma rays is called ‘radioactivity’.

Question 2.
By whom radioactivity is detected in pitchblende?
Answer:
Marie curie and Purie curie.

Question 3.
Define ‘Artificial Radioactivity’.
Answer:
The phenomenon by which even light elements are made radioactive, by artificial or induced methods, is called ‘Artificial radioactivity’ or ‘Man – made radioactivity’.

Question 4.
Define ‘One curie’.
Answer:
It is defined as the quantity of a radioactive substance which undergoes 3.7 × 1010 disintegrations in one second. This is actually close to the activity of 1 g of radium 226.
Curie = 3.7 × 1010 disintegrations per second.

Question 5.
In which elements artifical radioactivity is induced?
Answer:
Boron and aluminum

Question 6.
What is alpha decay (α decay)? give an example.
Answer:
A nuclear reaction in which an unstable parent nucleus emits an alpha particle and forms a stable daughter nucleus is called ‘alpha decay’.
E.g. Decay of uranium (U238) to thorium (Th234) with the emission of an alpha particle.
92U238→90Th234+2He4 (α – decay).

Question 7.
What is beta decay (β decay)? Give an example?
Answer:
A nuclear reaction, in which an unstable parent nucleus emits a beta particle and forms a stable daughter nucleus, is called ‘beta decay’.
E.g. Beta decay of phosphorous.
15P32→16S32+−1e0 (β – decay)

Question 8.
What is gamma decay (γ decay)?
Answer:
In a γ – decay, only the energy level of the nucleus changes. The atomic number and mass number of the radioactive nucleus remain the same.

Question 9.
State the value of Roentgen in terms of Coulomb.
Answer:
Roentgen = 2.58 × 10-4 Coulomb in / kg of air.

Question 10.
Define ‘nuclear fission’ Give an example.
Answer:
The process of breaking (splitting) up of a heavier nucleus into two smaller nuclei with the release of a large amount of energy and a few neutrons are called ‘nuclear fission’.
E.g. Nuclear fission of a uranium nucleus (U235)
92U235+0n1→56Ba141+36Kr92+30n1+Q( energy )

Question 11.
Define ‘Nuclear fusion’ Give an example.
Answer:
The process in which two light nuclei combine to form a heavier nucleus is termed as ‘Nuclear fusion’.
E.g. 1H2+1H2→2He4+Q( Energy )

Question 12.
Write down the types of the nuclear reactor.
Answer:
Breeder reactor, fast breeder reactor, pressurized water reactor, pressurized heavy water reactor, boiling water reactor, water – cooled reactor, gas – cooled reactor, fusion reactor and thermal reactor are some types of nuclear reactors, which are used in different places worldwide.

Question 13.
What is the safe limit of receiving radioactive radiations?
Answer:
100 m R per week

VIII. Answer in the details:

Question 1.
Explain the principle and working of an atom bomb?
Answer:
Atom bomb:
(i) The atom bomb is based on the principle of the uncontrolled chain reaction. In an uncontrolled chain reaction, the number of neutrons and the number of fission reactions multiply almost in a geometrical progression.

(ii) This releases a huge amount of energy in a very small time interval and leads to an explosion.

Structure:
(i) An atom bomb consists of a piece of fissile material whose mass is subcritical. This piece has a cylindrical void.

(ii) It has a cylindrical fissile material which can fit into this void and its mass is also subcritical. When the bomb has to be exploded, this cylinder is injected into the void using a conventional explosive.

(iii) The two pieces of fissile material join to form the supercritical mass, which leads to an explosion. During this explosion, a tremendous amount of energy in the form of heat, light and radiation is released.

(iv) A region of very high temperature and pressure is formed in a fraction of a second along with the emission of hazardous radiation like y rays, which adversely affect the living creatures. This type of atom bombs was exploded in 1945 at Hiroshima and Nagasaki in Japan during World War II.

Question 2.
State and define the units of radioactivity.
Answer:
Curie : It is the traditional unit of radioactivity. It is defined as the quantity of a radioactive substance which undergoes 3.7 × 1010 disintegrations in one second. This is actually close to the activity of lg of radium 226. 1 curie = 3.7 × 1010 disintegrations per second.

Rutherford (Rd) : It is another unit of radioactivity. It is defined as the quantity of a radioactive substance, which produces 106 disintegrations in one second.
1 Rd = 106 disintegrations per second.

Becquerel (Bq) : It is the SI unit of radioactivity is becquerel. It is defined as the quantity of one disintegration per second.

Roentgen (R) : It is the radiation exposure of γ and x-rays is measured by another unit called roentgen. One roentgen is defined as the quantity of radioactive substance which produces a charge of 2.58 × 10-4 coulomb in 1 kg of air under standard conditions of pressure, temperature and humidity.

Question 3.
Write down the features of nuclear fission and nuclear fusion.
Answer:

Nuclear FissionNuclear Fusion
1. The process of breaking up (splitting) of a heavy nucleus into two smaller nuclei is called ‘nuclear fission’.1. Nuclear fusion is the combination of two lighter nuclei to form a heavier nucleus.
2. Can be performed at room temperature.2. Extremely high temperature and pressure are needed.
3. Alpha, beta and gamma radiations are emitted.3. Alpha rays, positrons, and neutrinos are emitted.
4. Fission leads to emission of gamma radiation. This triggers the mutation in the human gene and causes genetic transform diseases.4. Only light and heat energy are emitted.

Question 4.
Write down the medical and industrial application of radioisotopes?
Answer:

  1. Radio sodium (Na24) is used for the effective functioning of the heart.
  2. Radio – Iodine (I131) is used to cure goitre.
  3. Radio – Iron is (Fe59) is used to diagnose anaemia and also to provide treatment for the same.
  4. Radio Phosphorous (P32) is used in the treatment of skin diseases.
  5. Radio Cobalt (Co60) and radio – gold (Au198) are used in the treatment of skin cancer.
  6. Radiations are used to sterilize the surgical devices as they can kill the germs and microbes.
  7. Radio cobalt (Co60) and radio – gold (Au198) are used in the treatment of skin cancer.
  8. Radiations are used to sterilize the surgical devices as they can kill the germs and microbes.

Question 5.
Write a note about stellar energy.
Answer:
The stars like our Sun emit a large amount of energy in the form of light and heat. This energy is termed as the stellar energy. Where does this high energy come from? All-stars contain a large amount of hydrogen. The surface temperature of the stars is very high which is sufficient to induce fusion of the hydrogen nuclei.

Fusion reaction that takes place in the cores of the Sun and other stars results in an enormous amount of energy, which is called as ‘stellar energy’. Thus, nuclear fusion or thermonuclear reaction is the source of light and heat energy in the Sun and other stars.

IX. Additional HOT Questions

Question 1.
Why is neutron so effective as bombarding particle?
Answer:
A neutron carries no charge. It easily penetrates even a heavy nucleus without being repelled or attracted by nucleus and electrons. So it serves as an ideal projectile for starting a nuclear reaction.

Question 2.
Is there any difference between electron and a beta particle.
Answer:
Basically, there is no difference between an electron and a beta particle. β particle is the name given to an electron emitted from the nucleus.

Question 3.
Why are the control rods made of cadmium?
Answer:
Cadmium has high cross – section for the absorption of neutrons.

Question 4.
Name two radioactive elements that are not found in observable quantities why is it so?
Answer:
Tritium and Plutonium are two radioactive elements that are not found in observable quantities in the universe.
It is because half-life period of each of two elements is very short compared to the age of the universe.


Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 23, Visual Communication, tamilnadu board, 10th Science, Computer Science,

I. Choose the correct answer:

Question 1.
Which software is used to create animation?
(a) Paint
(b) PDF
(c) MS Word
(d) Scratch.
Answer:
(d) Scratch.

Question 2.
All files are stored in the:
(a) Folder
(b) box
(c) Pai
(d) Scanner
Answer:
(a) Folder

Question 3.
Which is used to build scripts?
(a) Script area
(b) Block palette
(c) Stage
(d) Sprite.
Answer:
(a) Script area

Question 4.
Which is used to edit programs?
(a) Inkscape
(b) Script editor
(c) Stage
(d) Sprite
Answer:
(b) Script editor

Question 5.
Where you will create the category of blocks?
(a) Block palette
(b) Block menu
(c) Script area
(d) Sprite.
Answer:
(b) Block menu

II. Match the following:

Question 1.

1. Script Area(a) Type notes
2. Folder(b) Animation software
3. Scratch(c) Edit programs
4. Costume editor(d) Store files
5. Notepad(e) Build Scripts

Answer:

  1. (e) Build Scripts
  2. (d) Store files
  3. (b) Animation software
  4. (c) Edit programs
  5. (a) Type notes.

III. Answer the following:

Question 1.
What is Scratch?
Answer:
‘Scratch’ is a software used to create animations, cartoons and games easily. Scratch, on the other hand, is a visual programming language. It was developed in the Massachusetts Institute of Technology (MIT) Media Lab to make programming easier and more fun to learn.

Question 2.
Write a short note on editor and its type?
Answer:
There are two types of editors. They are (i) Script editor (ii) Costume editor.
Editors are used to edit your programs or your sprite’s pictures. The script editor has three main parts: Script area, Block menu and Block palette. When costume editor tab is chosen, Click → File / New to create new project.

Question 3.
What is Stage?
Answer:
The stage is the background appearing when we open the scratch window. The background will most often be white. You can change the background colour as you like.

Samacheer Kalvi 10th Science Visual Communication Additional Questions Solved

I. Choose the correct answer.

Question 1.
The characters on the background of a scratch window are known as _______.
(a) stage
(b) screen
(c) sprite
(d) script.
Answer:
(c) sprite

Question 2.
Which button is click, it shows the list of all programs in the computer?
(a) My computer
(b) START
(c) Recycle Bin
(d) Explorer
Answer:
(b) START

Question 3.
Choose the correct pair for the following _______.
(a) Stage – bottom left
(b) Sprite list – top left
(c) Script tab – right
(d) None of these.
Answer:
(c) Script tab – right

Question 4.
The device which helps in explaining the concepts easily through pictures is known as:
(a) Visual communication device
(b) Paint
(c) Notepad
(d) Scratch
Answer:
(a) Visual communication device

Question 5.
Choose the correct statement from the following _______.
(a) The output we get from any application is called folder.
(b) Cinema is a good example of VCD.
(c) The characters on the background of a scratch window are known as a stage.
(d) The scratch editor has four main parts.
Answer:
(b) Cinema is a good example of VCD.

Question 6.
Which company was developed by Scratch software?
(a) Massachusetts Institute of Technology (MIT)
(b) Microsoft corporation
(c) Sun micro system
(d) Oracle corporation
Answer:
(a) Massachusetts Institute of Technology (MIT)

Question 7.
The output we get from any application is commonly referred to as _______.
(a) file
(b) folder
(c) hardware
(d) software.
Answer:
(a) file

Question 8.
Choose the correct pair:
(a) Script – Event
(b) Mouse – Output
(c) Visual – blackboard
(d) NEW – Start
Answer:
(a) Script – Event

Question 9.
When we _____ on the mouse, the popup menu appears.
(a) right – click
(b) left click
(c) click
(d) right.
Answer:
(a) right-click

Question 10.
Choose the correct statement:
(a) The scratch editor has two main parts.
(b) The stage background will most often be black.
(c) Block menu, where you build scripts
(d) The script editor right pane also contains two additional tabs, costumes and sounds.
Answer:
(d) The script editor right pane also contains two additional tabs, costumes and sounds.

Question 11.
The list of all programs loaded in the computer is shown when you click _______ button.
(a) Home
(b) list
(c) All programs
(d) start.
Answer:
(d) start.

Question 12.
Which device helps in explaining the concepts easily through pictures?
(a) Audiometer
(b) Video meter
(c) Visual audio device
(d) Visual communication device.
Answer:
(d) Visual communication device.

Question 13.
Which one of the following is a good example of a visual communication device?
(a) Theatre
(b) Cinema
(c) Exhibitions
(d) poster making.
Answer:
(b) Cinema

Question 14.
VCD means _______.
(a) Virtual compact disk
(b) Video compact disc
(c) Visual contract device
(d) Visual communication device.
Answer:
(d) Visual communication device.

Question 15.
Which one of the following is a visual programming language?
(a) Visual Basic
(b) Scratch
(c) Visual C++
(d) paint.
Answer:
(b) Scratch

Question 16.
Expand MIT _______.
(a) Maritime Institute of Technology
(b) Madras Institute of Technology
(c) Massachusetts Institute of Technology
(d) Maldives Institute of Technology.
Answer:
(c) Massachusetts Institute of Technology

Question 17.
The Scratch editors consists of ______ main parts.
(a) 2
(b) 3
(c) 4
(d) 5.
Answer:
(b) 3

Question 18.
Pick the odd one out _______.
(a) Stage
(b) Screen
(c) Sprite
(d) Script editor.
Answer:
(b) Screen

Question 19.
_______ is the background appearing when we open the scratch Window.
(a) Stage
(b) Screen
(c) Sprite
(d) Script.
Answer:
(a) Stage

Question 20.
What is the default colour of the stage?
(a) red
(b) yellow
(c) white
(d) black.
Answer:
(c) white

Question 21.
Find the correct statement from the following?
(a) The background colour of the stage can be changed.
(b) The background colour of the stage cannot be changed.
Answer:
(a) The background colour of the stage can be changed.

Question 23.
The _____ pane also contains two additional tabs like costumes and sounds.
(a) left
(b) right
(c) centre
(d) bottom.
Answer:
(b) right

Question 24.
Find the false statement from the following.
(a) When the costume tab is chosen, the costume editor appears in red colour.
(b) When the costume tab is chosen, the costume editor appears in blue colour.
Answer:
(b) When the costume tab is chosen, the costume editor appears in blue colour.

Question 25.
What is the command used to create a new project?
(a) File →New
(b) File → project New
(c) File → New project
(d) File → project.
Answer:
(a) File → New

Question 26.
Click the _____ flag at the top right comer of the stage to run your program.
(a) red
(b) blue
(c) green
(d) yellow.
Answer:
(c) green

Question 27.
Which is not a part of script editor?
(a) sprite
(b) script area
(c) Block menu
(d) Block palette.
Answer:
(a) sprite

Question 28.
Click the scripts tab and find the play sound block from the ________ menu.
(a) scripts
(b) events
(c) sound
(d) audio.
Answer:
(c) sound

II. Match the following:

Question 1.

1. VCD(a) Storage space
2. File(b) Cinema
3. Folder(c) Software
4. Scratch(d) Specific purpose

Answer:

  1. (b) Cinema
  2. (d) Specific purpose
  3. (a) Storage space
  4. (c) Software.

Question 2.

1. Script tabs(a) Unknown place
2. Build scripts(b) Blocks tab
3. Right pane(c) Script area
4. Guide board(d) Costumes and sounds

Answer:

  1. (b) Blocks tab
  2. (c) Script area
  3. (d) Costumes and sounds
  4. (a) Unknown place.

III. Fill in the blanks:

Question 1.
______ and ____ plays a vital role in the working of the computer.
Answer:
Software, hardware.

Question 2.
In Windows OS, ______ application is used to draw pictures.
Answer:
paint.

Question 3.
In Windows OS, we can collect our notes in ______ application.
Answer:
Notepad.

Question 4.
The ______ tab on the right contains the blocks tabs and scripts area.
Answer:
Scripts.

Question 5.
Click the menu _____ drag a when green flag clicked the block to the scripts area.
Answer:
Script → Event.

Question 6.
Sound is present in _____ option.
Answer:
Script.

Question 7.
Visual programming was developed in the _______.
Answer:
Massachusetts Institute of Technology (MIT).

IV. Short Answer Questions

Question 1.
Define file.
Answer:
The output we get from any application is commonly referred to as ‘file’. Therefore the application for the specific purposes determines the nature of the file.

Question 2.
How can we save data and information in computer?
Answer:
We can save data and information in folders which accommodate a single file or multiple files. So all files are stored in the folder.

Question 3.
Define VCD. (Visual Communication Device)?
Answer:
The device which helps in explaining the concepts easily through pictures is known as ‘Visual Communication Device’. For example photos, audiovisuals, drawings, animations all these can be created easily with the help of the computer. Cinema is a good example of ‘Visual Communication Device’.

Question 4.
Write any four operating systems?
Answer:

  1. Windows
  2. UNIX
  3. LINUX
  4. iOS.

Question 5.
What are the three main parts of the script editor?
Answer:
The script editor has three main parts:

  • Script area: Where you build scripts.
  • Block menu: Where you choose the category of blocks (programming statements) to use.
  • Block palette: Where you choose the block to use.

Question 6.
How will you add sound using the costume tab?
Answer:
When the Costumes tab is chosen, the costume editor, Click File/New to create a new project and enter a project name.
Click File / New to create a new project and enter a project name.

Adding Sound:

  1. Click Spritel in the sprite list and click the Sounds tab.
  2. Try the meow sound already there. If you don’t like it, click the speaker icon to choose a different sound from the sound library.
  3. Click the Scripts tab and find the play sound block from the Sound menu. Add this block to the when space key pressed script. (Select the sound you want from the drop-down list.)
  4. Run your program.

Question 7.
Explain how will you create a new project?
Answer:
Click File / New to create a new project and enter a project name.

V. Long Answer Questions

Question 1.
Explain adding sound with an example.
Answer:
Adding Sound:

  1. Click Spritel in the sprite list and click the Sounds tab.
  2. Try the meow sound already there. If you don’t like it, click the speaker icon to choose a different sound from the sound library.
  3. Click the Scripts tab and find the play sound block from the Sound menu. Add this block when space key pressed script. (Select the sound you want from the drop-down list.)
  4. Run your program.

Example:
Program for print the word “Hello” with sound:

1. Click events in script option.

2. Drag “When Clicked” tab to script area.

3. Click Looks in script option. Drag “say” to script area.

4. Type “Hello “ word in say tab.

5. Click sounds in script option. Drag play sound to script area. Choose the hello sound from the audio file.

6. From File menu choose the Save option.

7. Click the green flag at the top right comer of the stage window to run the program.


Samacheer Kalvi 10th Science Solutions Chapter 23 Visual Communication 8

Question 2.
Explain how will you give movements and loops. Give an example.
Answer:
Click the menu Script → Event, drag a when green flag clicked a block to the scripts area. Your scripts area should look like this:

Click the menu Script → Motion menu, drag a goto x : 0, y : 0 blocks to the scripts area and snap it to the bottom of the when green flag clicked the block.
Your script should look like this:


Add a move 10 steps block to the bottom of your script and change the 10 into 100.

Click the green flag at the top right comer of the stage to run your program.


Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 22, Environmental Management, tamilnadu board, biology,

I. Fill in the blanks.

Question 1.
Deforestation leads to ______ in rainfall.
Answer:
Reduction

Question 2.
Removal of soil particles from the land is called ______
Answer:
Soil erosion

Question 3.
Chipko movement is initiated against ______
Answer:
the cutting down of trees

Question 4.
______ is a biosphere reserve in Tamilnadu.
Answer:
Nilgiris

Question 5.
Tidal energy is ______ type of energy.
Answer:
Non-conventional or renewable

Question 6.
Coal, petroleum and natural gas are called ______ fuels.
Answer:
Fossil

Question 7.
______ is the most commonly used fuel for the production of electricity.
Answer:
Coal

II. State whether True or False. If false, write the correct statement:

Question 1.
Biogas is a fossil fuel.
Answer:
False
Correct statement: Biogas is the mixture of methane, hydrogen sulphide, carbon-di-oxide and hydrogen.

Question 2.
Planting trees increase the groundwater level.
Answer:
True

Question 3.
Habitat destruction caused loss of wildlife.
Answer:
True

Question 4.
Nuclear energy is renewable energy.
Answer:
False
Correct statement: Nuclear energy is a non-renewable energy source. The material used in nuclear plants is not renewable.

Question 5.
Overgrazing prevents soil erosion.
Answer:
False
Correct statement: During overgrazing, most of the plants are eaten up. If the plants or vegetation is retained, the soil is not exposed. Soil erosion occurs due to overgrazing.

Question 6.
Poaching of wild animals is a legal act.
Answer:
False
Correct statement: Poaching should be prohibited.

Question 7.
The national park is a protected park.
Answer:
True

Question 8.
Wildlife protection act was established in 1972.
Answer:
True

III. Match the following:

Question 1.

Column AColumn B
1. Soil erosion(a) energy saving
2. Bio-gas(b) acid rain
3. Natural gas(c) removal of vegetation
4. Greenhouse gas(d) renewable energy
5. CFL bulbs(e) CO2
6. Wind(f) non-renewable energy
7. Solid waste(g) lead and heavy metals

Answer:

  1. (c) Removal of vegetation
  2. (d) Renewable energy
  3. (f) Non-renewable energy
  4. (e) CO2
  5. (a) energy saving
  6. (b) acid rain
  7. (g) Lead and heavy metals

IV. Choose the correct answer:

Question 1.
Which of the following is/are a fossil fuel?
i. Tar
ii. Coal
iii. Petroleum
(a) i only
(b) i and ii
(c) ii and iii
(d) i, ii and iii
Answer:
(c) ii and iii

Question 2.
What are the steps will you adopt for better waste management?
(a) reduce the amount of waste formed
(b) reuse the waste
(c) recycle the waste
(d) all of the above
Answer:
(d) all of the above

Question 3.
The gas released from vehicles exhaust is _________
i. Carbon monoxide
ii. Sulphur dioxide
iii. Oxides of nitrogen
(a) i and ii
(b) i and iii
(c) ii and iii
(d) i, ii and iii
Answer:
(d) i, ii and iii

Question 4.
Soil erosion can be prevented by:
(a) deforestation
(b) afforestation
(c) over growing
(d) removal of vegetation
Answer:
(b) afforestation

Question 5.
A renewable source of energy is ______
(a) petroleum
(b) coal
(c) nuclear fuel
(d) trees
Answer:
(d) trees

Question 6.
Soil erosion is more where there is:
(a) no rain fall
(b) low rainfall
(c) rain fall is high
(d) none of these
Answer:
(c) rain fall is high

Question 7.
An inexhaustible resources is _______
(a) wind power
(b) soil fertility
(c) wildlife
(d) all of the above
Answer:
(d) all of the above

Question 8.
Common energy source in village is:
(a) electricity
(b) coal
(c) biogas
(d) wood and animal dung
Answer:
(d) wood and animal dung

Question 9.
The greenhouse effect refers to _____
(a) cooling of Earth
(b) trapping of UV rays
(c) cultivation of plants
(d) warming of Earth
Answer:
(d) warming of Earth

Question 10.
A cheap, conventional, commercial and inexhaustible source of energy is:
(a) hydropower
(b) solar energy
(c) wind energy
(d) thermal energy
Answer:
(c) wind energy

Question 11.
Global warming will cause _______
(a) raise in the level of oceans
(b) melting of glaciers
(c) sinking of islands
(d) all of these
Answer:
(d) all of these

Question 12.
Which of the following statement is wrong with respect to wind energy?
(a) wind energy is a renewable energy
(b) the blades of wind mill are operated with the help of electric motor
(c) production of wind energy is pollution free
(d) usage of wind energy can reduce the consumption of fossil fuels
Answer:
(b) the blades of wind mill are operated with the help of electric motor

V. Answer in a Sentence.

Question 1.
What will happen if trees are cut down?
Answer:
Soil erosion occurs and ecological imbalance takes place if trees are cut down.

Question 2.
What would happen if the habitat of wild animals is disturbed?
Answer:
If the habitat of wild animal is disturbed it leads to extinction of animals or on the verge of extinction.

Question 3.
What are the agents of soil erosion?
Answer:
The high velocity of wind, air currents, flowing water, landslide, human activities such as deforestation, farming and mining, and overgrazing by cattle are the agents of soil erosion.

Question 4.
Why fossil fuels are to be conserved?
Answer:
The formation of fossil fuels is a very slow process and takes very long period of time for renewals so fossil fuels are to conserved.

Question 5.
Solar energy is renewable energy. How?
Answer:
Solar energy is renewable, free source of energy, that is sustainable and totally inexhaustible.

Question 6.
How are e- wastes generated?
Answer:
e-wastes are spoiled, out dated, non-repairable, electrical and electronic devices like computer components electronic and electrical appliances.

VI. Short Answer Questions

Question 1.
What is the importance of rainwater harvesting?
Answer:
The importance of rainwater harvesting is as follows:

  • overcome the rapid depletion of groundwater levels.
  • To meet the increased demand for water.
  • Reduces flood and soil erosion.
  • Water stored in-ground is not contaminated by human and animal wastes and hence can be used for drinking purpose.

Question 2.
What are the advantages of using biogas?
Answer:

  1. It bums without smoke and therefore causes less pollution.
  2. An excellent way to get rid of organic wastes like bio-waste and sewage material.
  3. Left over slurry is a good manure rich in nitrogen and phosphorus.
  4. It is safe and convenient to use.
  5. It can reduce the amount of greenhouse gases emitted.

Question 3.
What is the environmental effect caused by sewage?
Answer:

  • Sewage is the leading polluter of water resources in India.
  • Different species of fishes are killed.
  • Contaminated water can cause diseases such as e-coli, diarrhoea and hepatitis A.

Question 4.
What are the consequences of deforestation?
Answer:
Deforestation gives rise to ecological problems like floods, drought, soil erosion, loss of wild life, extinction of species, imbalance of biogeochemical cycles, alteration of climatic conditions and desertification.

VII. Long Answer Questions

Question 1.
How does rainwater harvesting structures recharge groundwater?
Answer:
Rainwater harvesting is a technique of collecting and storing rainwater for future use. The main purpose of rainwater harvesting is to make the rainwater percolate under the ground, so as to recharge ‘groundwater level’.

Methods of rainwater harvesting
(i) Rooftop rainwater harvesting: The rainwater that falls on the roof of the houses, apartments and commercial buildings, etc, is collected and stored in the surface tank and is used for domestic purpose.

(ii) Recharge pit: The collected rainwater is directed into the percolation pits through pipes for Alteration. After Alteration, the rainwater enters the recharge pits or ground wells.

  • Digging of tanks or lakes (Eris): Eris is constructed in such a way that, if the water in one eri overflows, it automatically gets diverted to the eri of the next village, as these eris are interconnected.
  • Ooranis: These are small ponds to collect rainwater. They are used for various domestic purposes.

Question 2.
How will you prevent soil erosion?
Answer:

  1. Retain vegetation cover, so that soil is not exposed.
  2. Cattle grazing should be controlled.
  3. Crop rotation and soil management improve soil organic matter.
  4. Runoff water should be stored in the catchment.
  5. Reforestation, terracing and contour ploughing.
  6. Wind speed can be controlled by planting trees in form of a shelter belt.

Question 3.
What are the sources of solid wastes? How are solid wastes managed?
Answer:
Solid wastes mainly include municipal wastes, hospital wastes, industrial wastes and e-wastes, etc. The solid wastes are dumped in the soil, which results in landscape pollution. Solid-waste management involves the collection, treatment and proper disposing of solid material that is discarded from the household and industrial activities.

Methods of solid wastes disposal:

  • Segregation: It is the separation of different type of waste materials like biodegradable and non-biodegradable wastes.
  • Sanitary landfill: Solid wastes are dumped into low lying areas. The layers are compacted by trucks to allow settlement. The waste materials get stabilised in about 2-12 months. The organic matter undergoes decomposition.
  • Incineration: It is the burning of non-biodegradable solid wastes (medical wastes) in the properly constructed furnace at high temperature.
  • Composting: Biodegradable matter of solid wastes is digested by microbial action or earthworms and converted into humus.

Question 4.
Enumerate the importance of forest.
Answer:
Forests are an important component of our environment and are dominated by microorganisms, flowering plants, shrubs, climbers, dense trees and provide a vast habitat for wild animals. Forests also contribute to the economic development of our country. Forests are vital for human life, it is a source for a wide range of renewable natural resource. They provide wood, food, fodder, fibre and medicine.

Forests are major factor of environmental concern. They act as a carbon sink, regulate climatic conditions, increase rainfall, reduce global warming, prevent natural hazards like flood and landslides, protect wildlife and also act as catchments for water conservation. They also play a vital role in maintaining ecological balance.

Question 5.
What are the consequences of soil erosion?
Answer:
The consequences of soil erosion are as follows:

  • It has led to increased pollution and sedimentation in streams and rivers.
  • Clogging the waterways and causing a decrease in fish species.
  • Degraded lands often have less ability to hold on to water.
  • Topsoil is removed.
  • Topsoil quality is reduced.
  • No medium crops to grow in soil with poor quality.
  • Use of artificial fertilizers.
  • Disrupts ecosystem.

Question 6.
Why is the management of forest and wildlife resource considered as a challenging task?
Answer:
People would consider forest is a source of raw materials for the factories and industries, and utilise it for development of human without considering about other organism. There are many stake holders of forest. They are those people who are directly or indirectly involved in forest. Management of forest and called life has to take into account the interest of all stake holders which become a challenging task.

VIII. Assertion and Reasoning Questions

In each of the following question, a statement of assertion (A) is given and a corresponding statement of Reason (R). Of the four statements given below mark the correct answer.
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.
(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.
(c) Assertion is true but the reason is false.
(d) Both assertion and reason are false.

Question 1.
Assertion: Rainwater harvesting is to collect and store rainwater.
Reason: Rainwater can be directed to recharge the underground water source.
Answer:
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.

Question 2.
Assertion: Energy-efficient bulbs like CFL must be used to save electric energy.
Reason: CFL bulbs are costlier than ordinary bulbs, hence using ordinary bulbs can save our money.
Answer:
(c) Assertion is true but the reason is false.

IX. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Although coal and petroleum are produced by the degradation of biomass, yet we need to conserve them. Why?
Answer:

  • The coal and petroleum reserves can get exhausted, if we use them at a rapid rate.
  • The formation of fossil fuel is a very slow process and takes a very long time for renewal.
  • It is necessary to conserve the resource, for the future generation, by reducing their consumption.

Question 2.
What are the objectives for replacing non-conventional energy resources from conventional energy resources?
Answer:
Non conventional energy resources are non-polluting renewable sources which are environmentally clean. It is available in unlimited amount in nature and they can be renewed over a short period of time inexpensive and can be harvested continuously.

Question 3.
Why is the Government imposing a ban on the use of polythene bags and plastics? Suggest alternatives. How is this ban likely to improve the environment?
Answer:
Government is imposing a ban on the use of plastic bags and plastics because,

  • Plastics pollute on land, rivers, ponds and all water bodies and soil, etc.
  • Burning of plastic in open air leads to environmental pollution, due to the release of poisonous gas.
  • The accumulation of plastic bags and plastics prevent the seeping of water into the Earth, which brings down the levels of groundwater.
  • Plastic bags can travel long distances by wind and water. They litter our landscapes and water bodies.

Alternatives:

  • Bring your own containers and bags to buy things from the shop.
  • Use paper wraps or compostable bags with cloth or brown paper.

Improvement of the environment on plastic ban:

  • Improve the health of individuals.
  • Driving to innovate alternatives.
  • Plastic pollution reduced.
  • The nation is safe.

X. Value-Based Questions

Question 1.
Why is it not possible to use solar cells to meet our energy needs? State three reason to support to your answer.
Answer:
In solar cells, the solar panel convert solar energy into electricity, which stored in storage battery. The storage battery gives direct current, which is to be converted into alternating current by an suitable appliances before it can be used to run various, devices. So, it increases the cost of using panels as the source of energy.

In the solar cells the energy is obtained only during the day, when the sun shines. So the solar cells is not used to meet our energy needs.

Question 2.
How would you dispose of the following wastes?

  1. Domestic wastes like vegetable peels
  2. Industrial wastes like metallic cans

Can the disposal protect the environment? How?
Answer:

  1. Domestic wastes have to be thrown out with the trash.
  2. Do vermiform composting system for vegetable wastes which can be used as a manure. Industrial wastes like metallic cans can be recycled.

Question 3.
List any three activities based on 3R approach to conserve natural resources.
Answer:
Recycling : Using recycled material of glass plastic, paper, metal etc.
Reuse : Repeating use of items.
Reduce : Avoid the use of materials which increases the solid waste.
Use of public transport instead of personal transport to reduce to consumption of fuel. Use of materials such as paper should be preferred.

Textbook Activities Solved

Question 1.
Collect information regarding the
(i) Tehri Dam project
(ii) Sardar Sarovar Dam project
Answer:
(i) Tehri Dam project:
Tehri Dam is the highest dam in India and one of the highest in the world. It is a multi-purpose rock and earth-filled embankment dam on the Bhagirathi River near Tehri in Uttarakhand, India. It is the primary dam of the THDC India limited and the Tehri hydro-electric complex. The Tehri Dam withholds a reservoir for irrigation, municipal water supply and the generation of 1000 megawatts of hydroelectricity.

(ii) Sardar Sarovar dam project:
Sardar Sarovar Dam is a gravity dam on the Narmadha river near Navagam. It is a part of the Narmada valley project, a large hydraulic engineering project.
Benefits:

  • Provides irrigation facilities.
  • Drinking water supply.
  • There are two powerhouses, red bed powerhouse and canal head powerhouse with a capacity of 1200 MW and 250 MW, respectively.
  • It provides flood protection.
  • Wildlife sanctuaries are maintained.
  • Development of fisheries.
  • Water supply for industries.
  • Protection of conserved forests.

Samacheer Kalvi 10th Science Environmental Management

Additional Questions Solved

I. Fill in the blanks.

Question 1.
______ is used for generation of _____, at thermal power plants.
Answer:
Coal, Electricity

Question 2.
Petroleum is refined to produce _____ and _____, which are used to run automobiles, trucks, trains and ships, etc.
Answer:
Petrol, Diesel

Question 3.
______ and ______ obtained from petroleum are used as domestic fuel.
Answer:
Kerosene, LPG

Question 4.
Solar energy is obtained from ______
Answer:
Sun

Question 5.
Solar cells convert sunlight directly into ______
Answer:
Electricity

Question 6.
_______ plants convert the kinetic energy of flowing water into electricity.
Answer:
Hydropower

Question 7.
The 3R approach such as _____, _____ and ______ may be followed to effective waste management.
Answer:
Reduce, Reuse and Recycle

Question 8.
_______ is a reserved area for the conservation of entire wildlife including plants and animals.
Answer:
National park

Question 9.
______ is a place reserved exclusively for the use of animals.
Answer:
Sanctuary

Question 10.
Unwanted, non-working and out-dated electronic products become ______
Answer:
e-waste

Question 11.
In India, the forests are classified into ______ forests and ______ forests.
Answer:
Reserved, Protected

Question 12.
The small ponds to collect rainwater is called ______
Answer:
Ooranis

II. Write true or false for the following statements. Correct the false statements:

Question 1.
Conservation of natural resources makes an important contribution to the social and economic development of the country.
Answer:
True

Question 2.
Overexploitation and shrinking of forest resulted, the increase of animals and the nourishment of wildlife.
Answer:
False
Correct statement: Overexploitation and shrinking of forest resulted, in animals becoming extinct, some are threatened and some are on the verge of extinction.

Question 3.
The potential energy possessed by the wind, due to lower speed, that can be converted into chemical power by wind turbines.
Answer:
False
Correct statement: The kinetic energy possessed by the wind is due to its high speed, that can be converted into mechanical power by wind turbines.

Question 4.
The main purpose of rainwater harvesting is to make the rainwater, run on its surface of Earth.
Answer:
False
Correct statement: The main purpose of rainwater harvesting is to make the rainwater, to percolate under the ground, so as to recharge the groundwater level.

Question 5.
The burning of non-biodegradable solid wastes (medical wastes) in the properly constructed furnace at high temperature is called electronic wastes.
Answer:
False
Correct statement: The burning of non-biodegradable solid wastes (medical wastes) in the properly constructed furnace at high temperature is called incineration.

III. Match the following:

Question 1.

1. Van Mahotsav(a) Destruction of forests
2. Bombay Natural History Society(b) Crude oil
3. Deforestation(c) Photovoltaic devices
4. Erosion(d) Afforestation programme
5. Solar cells(e) Conservation of wildlife
6. Petroleum(f) Removal of an upper layer of soil

Answer:

  1. (d) Afforestation programme
  2. (e) Conservation of wildlife
  3. (a) Destruction of forests
  4. (f) Removal of an upper layer of soil
  5. (c) Photovoltaic devices
  6. (b) Crude oil

IV. Choose the correct answer:

Question 1.
The new sources of energy are termed as _______
(a) fossil fuel
(b) Conventional energy resources
(c) Non-conventional sources of energy
(d) conservation
Answer:
(c) non-conventional sources of energy

Question 2.
Disposable plastic plates should not be used because:
(a) They are made of materials with light weight
(b) They are made of toxic materials.
(c) They are made of biodegradable materials.
(d) They are made of non-biodegradable materials.
Answer:
(d) They are made of non-biodegradable materials.

Question 3.
The other name for Biogas is ______
(a) Natural gas
(b) Nitrogen gas
(c) Gobar gas
(d) Shale gas
Answer:
(c) Gobar gas

Question 4.
Wildlife includes:
(a) Wild animals only
(b) Wild plants only
(c) Wild plants and animals
(d) All plants and animals
Answer:
(d) All plants and animals

Question 5.
E-wastes are generally called as _______
(a) garbages
(b) electronic waste
(c) decomposition
(d) solid wastes
Answer:
(b) electronic waste

V. Answer the following shortly.

Question 1.
Why should we conserve forests and wild life?
Answer:
We should conserve forest and wild life to preserve the biodiversity, so as to avoid the loss of ecological stability. Without proper management of forest and wild life, the quality of soil, the water sources, and even the amount of rainfall may be affected.

Question 2.
What are the effects of deforestation?
Answer:
Deforestation gives rise to ecological problems like floods, drought, soil erosion, loss of wildlife, extinction of species, imbalance of biogeochemical cycles, alteration of climatic conditions and desertification.

Question 3.
Name the organisation involved in wild life conservation.
Answer:
Organisations Involved in Conservation of Wildlife

  1. Indian Board for WildLife (IBWL)
  2. World Wildlife Fund (WWF) for Nature
  3. World Conservation Union (WCN) ,
  4. International Union for Conservation of Nature and Natural resources (IUCN)
  5. Convention of International Trade in Endangered Species (CITES)
  6. Bombay Natural History Society
  7. Wild life Preservation Society of India, Dehradun

Question 4.
What are fossil fuels? How are they formed?
Answer:
The fossil fuels are petroleum, coal and natural gas. Due to the anaerobic decomposition of buried dead organisms, by a natural process over millions of years, energy-rich substances are formed. As the accumulating sediment layers produce heat and pressure, the remains of the organisms are gradually transformed into hydrocarbons.

Question 5.
Write the uses of solar cells.
Answer:

  1. It can be used for street lighting, traffic signals, water pumping, battery charging system etc.
  2. It is used in artificial satellites and space probes.
  3. It provides radio and TV transmission to remote areas.
  4. It is used in calculators, electronic toys and watches.

Question 6.
Write short notes about shale gas.
Answer:
Due to the compaction of small old rocks, which contain mud and minerals such as quartz and calcite, trapped beneath Earth’s surface and form the soft finely stratified sedimentary rock called shale. These rocks contain fossil fuels like oil and gas in their pores. This fuel is extracted by a technique called hydraulic fracturing.

Shale drilling could affect groundwater reserves, which can contaminate drinking water. It also affects the fertility of the soil. A million gallons of water is needed to break and release the shale gas which in turn can affect the fertility of the soil.
A million gallons of water is needed to break and release the shale gas, which in turn can affect the water table.

Question 7.
What is Tidal energy? What is it’s advantages?
Answer:
The energy obtained from the movement of water, due to ocean tides is called tidal energy. Tides are the rise and fall of sea level, caused by the combined effects of the gravitational force. A tidal stream is a fast-flowing body of water created by tides. Turbines are placed in tidal streams. When the tides hit the turbine, the turbine rotates and converts the tidal energy into electric energy.
Advantages:

  • It does not produce any pollution.
  • It does not use any fuel and does not produce any waste.
  • Tides are predictable, so tidal energy can be produced at any time.
  • Water is denser than air and therefore can generate electricity at lower speeds than wind turbines.

Question 8.
How is electric energy conserved?
Answer:

  • Use energy-efficient appliances to save electricity like compact fluorescent lamps (CFL), Light Emitting Diode [LED] bulbs and other electrical equipment.
  • Switch off the lights and fans, television and other electrical appliances, when not in use.
  • Switch off the mobile phone chargers when not in use.
  • Use more off solar radiation. Solar water heating system can be used instead of electric geysers.
  • Minimise the use of air conditioners.

Question 9.
What are the sources of e-waste? What is the environmental impact of e-waste?
Answer:
E-wastes are called electronic wastes, which includes the spoiled, outdated; non-repairable electrical and electronic devices. These wastes contain toxic metals like lead, cadmium, chromium and mercury, and also contains iron, copper, silicon, aluminium and gold, which can be recovered. The sources of e-wastes are:

  • Electronic device: Computers, laptops, mobile phones, printers, monitors, televisions, DVD players, calculators, toys and sports equipment.
  • Household electrical appliances: Refrigerators, washing machine, microwave oven, mixer, grinder and water heater, etc.
  • Accessories: Printing cartridges, batteries and chargers.

Environmental impact of e-wastes:
Disposal of any kind of electrical and electronic devices without knowledge can become the landfill and water pollutants.
Electronic equipment contains many heavy metals such as lead and cadmium that can cause severe soil and groundwater pollution. E-waste dumping yards and the places, nearby are polluted and cause a severe health hazard.

Question 10.
What is the 3R approach of ineffective waste management?
Answer:
Reduce, Reuse and Recycle are the 3R approach for effective waste management. Reducing the amount of waste, we produce is the best way to help the environment. Buying products with minimum packaging, not borrowing things which we do not use often, starting a compost bin, saving energy and water by turning are ways to reduce. Reuse materials in their original form or pass those materials on to others, who could use them. Paper cardboard, metals, plastics and textiles, etc can be recycled. The compost or reuse of bio-degradable wastes is also a kind of recycling.

Question 11.
What are non-conventional energy resources? What does it include?
Answer:
The energy resources available in an unlimited amount in nature and they can be renewed over a short period of time, inexpensive and can be harvested continuously is called the non-conventional energy resources.

The non-conventional energy resources include biofuel, bio mass-energy, geothermal energy, water energy (hydroelectric energy and tidal energy), solar energy, wave energy and wind energy.

Question 12.
What is the composition of Bio-gas? How is it formed?
Answer:

  • Bio-gas is the mixture of methane (75%), hydrogen sulphide, carbon dioxide and hydrogen.
  • It is produced by the decomposition of animal wastes (cow dung) and plant wastes in the ‘ absence of oxygen.
  • It is also commonly called as “Gobar gas”, as the starting material used is cow dung, which ~ means gobar in Hindi.

Question 13.
What are hydropower and hydropower electricity?
Answer:
Earth is covered with 71% of water. The technique to harness the water energy, from the flowing water is called the hydropower.

The electrical energy is derived from water flow and water falling from a height. In hilly areas, there is a continuous flow of water in large amounts falling from high slopes. The electricity produced by flowing water is called hydropower electricity.

VII. Answer the following in detail.

Question 1.
What are the aims of wildlife management?
Answer:
The main aim of wildlife conservation are:

  1. To control and limit exploitation of species.
  2. To preserve the plants and animals from extinction.
  3. Maintenance of threatened species and protect species which are on the verge of extinction.
  4. Preserve the endangered species.
  5. To study the ecological relationship of the plants and animals in natural habitat.
  6. Hunting and poaching should be prohibited.
  7. Establishment of National parks, Wildlife sanctuaries, protected areas and Biosphere reserves.

Question 2.
Explain in detail the classification of energy resources.
Answer:
Energy resources can be classified as renewable and non-renewable.
(i) Non-renewable (exhaustible) energy resources:
The energy obtained from sources that cannot renew themselves over a short period of time is called non-renewable energy. They include coal, petroleum, natural gas and nuclear power. The conventional energy resources account for 90% of the world’s production of commercial energy and nuclear power account for 10%.

(ii) Renewable (inexhaustible) energy resources:
Renewable (inexhaustible) energy resources are available in the unlimited amount in nature and they can be renewed over a short period of time, inexpensive and can be harnessed continuously. These are called non-conventional energy resources, which include biofuel, biomass energy, geothermal energy, water energy (hydroelectric energy and tidal energy), solar energy, wave energy and wind energy.

Question 3.
Write a note an shale gas. Explain the environment impact of shale gas.
Answer:
Shale refers to the soft finely stratified sedimentary rock that is formed from the compaction of small old rocks containing mud and minerals – such as quartz and calcite, trapped beneath earth’s surface. These rocks contain fossil fuels like oil and gas in their pores.

The fuel is extracted by a technique called hydraulic fracturing (drilling or well boring of sedimentary rocks layers to reach productive reservoir layers).

Environmental concerns of shale gas:

  1. Shale drilling could affect groundwater reserves, which can contaminate the drinking water resources and also affect the fertility of the soil.
  2. Million gallons of water is needed to break and release the shale gas, which intum can affect the water table.

Question 4.
(a) How does windmill work?
(b) List out the uses of wind energy and the advantages of wind energy.
Answer:
(a) A windmill is a machine, that converts the energy of wind, into rotational energy by broad blade attached to the rotating axis. When the blowing air strikes the blades of the windmill, it exerts force and causes the blades to rotate. The rotational movement of the blades operate the generator and the electricity is produced. The energy output from each windmill is coupled together to get electricity on a commercial scale.

(b) The uses of wind energy are as follows:

  • Generating electricity.
  • Run water pumps and flour mills, etc.
  • Rotatory motion of windmill is used to draw water from wells.

Advantages of wind energy:

  • Wind energy is a free, eco-friendly and renewable source of energy.
  • It does not cause pollution.
  • Expenses on periodic maintenance are low when compared to the other power sources.

Question 5.
(a) What are the sources of sewage or wastewater?
(b) Expiate the methods which involve in conventional wastewater treatment.
Answer:
(a) The sources of sewage or wastewater involve:

  • The domestic purpose or household activities
  • Dye and textile industries
  • Leather industries
  • Sugar and breweries industries
  • Paper and pulp industries

(b) The conventional wastewater treatment methods involve the following step:

  • Pre-screening: Wastewater generated from domestic and industrial activities is screened to remove soil and solid particulates.
  • Aeration: Screened wastewater is pumped to an aeration tank. Here the microbial contaminants are removed by the biological degradation, that occurs, in the presence of air.
  • Sedimentation process: In this process, the solid particles in suspension form are allowed to settle. The particles that settle out from the suspension is known as sludge.
  • Sludge removal: The sludge generated by the degradation process is transferred periodically from the tank for safe disposal.
  • Disinfection: Chlorination and ultraviolet (UV) radiation of treated water is required to remove any microorganism contamination.
  • Water recycling: The water will then be supplied for domestic or industrial purposes.

VII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
There are certain NGOs which ask people to donate their used clothes, toys, school books, house hold items. These NGOs segregate the collected items and distribute them to the needy people. What objectives do these NGOs fulfil by this initiatives?
Answer:
The objective behind this is Reuse and Recycle.

Question 2.
Name the national park, which was first established at Uttarakhand.
Answer:
Jim Corbett national park.

Question 3.
An environmentalist on your visit to your school suggested the use of 3R’s to same the environment. Explain the 3R’s.
Answer:
The 3R’s are Reduce, Reuse and Recycle.
Reuse : Instead of throwing thing away, try to find ways to use them again.
Recycle : Creating new product out of the materials from the old.
Reduce : It is the best way to help the environment by reducing the amount of waste you produce.

Question 4.
Where does India stand at the consumer of crude oil?
Answer:
India is the third-largest consumer of crude oil in the world after the United States and China.

Question 5.
Why does the white marble of Tajmahal become yellow?
Answer:
The Mathura oil refinery owned by Indian Oil Corporation presents around this area, which produces sulphur and nitrogen oxides. The white marble became yellow due to air pollution. The Government of India has set up emission standards around the monument to protect it from the damage.

Question 6.
Name the fourth oldest dam in the world? Where is it located?
Answer:
Kallanai Dam, which is also Called Grand Anicut, is the fourth oldest dam in the world. The dam is located on the river Kaveri, 20 km from the city of Tiruchirappalli.

Question 7.
Where is the world’s largest and tallest wind turbine located?
Answer:
The world’s largest and tallest wind turbine is situated in Hawai. One wind turbine can produce electricity for 300 homes.

Question 8.
Name the health effects of the following E-wastes.
Answer:

  • Lead: Damages the central and peripheral nervous system. It also affects brain development in children.
  • Chromium: Asthmatic bronchitis.
  • Cadmium: Accumulates in kidney and liver; Neural damage.
  • Mercury: Chronic damage to the brain and respiratory system.
  • Plastics including polyvinyl chloride [PVC]: Burning produces, dioxin, which can cause developmental and reproductive problems and damage the immune system.

Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 21, Health and Diseases, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
Tobacco consumption is known to stimulate the secretion of adrenaline. The component causing this could be _______.
(a) Nicotine
(b) Tannic acid
(c) Curcumin
(d) Leptin.
Answer:
(a) Nicotine

Question 2.
World ‘No Tobacco Day’ is observed on:
(a) May 31
(b) June 6
(c) April 22
(d) October 2
Answer:
(a) May 31

Question 3.
Cancer cells are more easily damaged by radiations than normal cells because they are _______.
(a) Different in structure
(b) Non-dividing
(c) Mutated Cells
(d) Undergoing rapid division.
Answer:
(d) Undergoing rapid division.

Question 4.
Which type of cancer affects lymph nodes and spleen?
(a) Carcinoma
(b) Sarcoma
(c) Leukemia
(d) Lymphoma
Answer:
(c) Leukemia

Question 5.
Excessive consumption of alcohol leads to _______.
(a) Loss of memory
(b) Cirrhosis of liver
(c) State of hallucination
(d) Suppression of brain function.
Answer:
(b) Cirrhosis of liver

Question 6.
Coronary heart disease is due to:
(a) Streptococci bacteria
(b) Inflammation of pericardium
(c) Weakening of heart valves
(d) Insufficient blood supply to heart muscles
Answer:
(d) Insufficient blood supply to heart muscles

Question 7.
Cancer of the epithelial cells is called _______.
(a) Leukaemia
(b) Sarcoma
(c) Carcinoma
(d) Lipoma.
Answer:
(c) Carcinoma

Question 8.
Metastasis is associated with:
(a) Malignant tumour
(b) Benign tumour
(c) Both (a) and (b)
(d) Crown gall tumour
Answer:
(a) Malignant tumour

Question 9.
Polyphagia is a condition seen in _______.
(a) Obesity
(b) Diabetes mellitus
(c) Diabetes insipidus
(d) AIDS.
Answer:
(b) Diabetes mellitus

Question 10.
Where does alcohol effect immediately after drinking?
(a) Eyes
(b) Auditory region
(c) Liver
(d) Central Nervous System
Answer:
(d) Central Nervous System

II. State whether True or False. If false, write the correct statement:

Question 1.
AIDS is an epidemic disease.
Answer:
False.
Correct Statement: AIDS is a viral disease.

Question 2.
Cancer-causing genes are called Oncogenes.
Answer:
True.

Question 3.
Obesity is characterized by tumour formation.
Answer:
False.
Correct Statement: Obesity is characterized by an accumulation of excess body fat with an abnormal increase in body weight.

Question 4.
In leukaemia, both WBCs and RBCs increase in number.
Answer:
False.
Correct Statement: Leukemia is characterized by an increase in the formation of white blood cells in the bone marrow and lymph nodes.

Question 5.
Study of the cause of the disease is called aetiology.
Answer:
False.
Correct Statement: Study of a cause of the disease is called Pathology.

Question 6.
AIDS is not transmitted by contact with a patient’s clothes.
Answer:
True.

Question 7.
Type 2 diabetes mellitus results due to insulin deficiency.
Answer:
False.
Correct Statement: In type 2 diabetes mellitus, Insulin production by the Pancreas is normal, but the target cells do not respond to insulin.

Question 8.
Carcinogens are cancer-causing agents.
Answer:
True.

Question 9.
Nicotine is a narcotic drug.
Answer:
False.
Correct Statement: Nicotine is a stimulant, highly harmful and poisonous substance, in Tobacco.

Question 10.
Cirrhosis is associated with the brain disorder.
Answer:
False.
Correct Statement: Liver damage resulting in Fatty liver which leads to Cirrhosis and formation of fibrous tissues.

III. Expand the following abbreviations:

Question 1.

  1. IDDM
  2. HIV
  3. BMI
  4. AIDS
  5. CHD
  6. NIDDM.

Answer:

  1. Insulin Dependent Diabetes Mellitus
  2. Human Immunodeficiency Vims
  3. Body Mass Index
  4. Acquired Immuno Deficiency Syndrome
  5. Coronary Heart Disease
  6. Non – Insulin Dependent Diabetes Mellitus.

IV. Match the following:

Question 1.

1. Sarcoma(a) Stomach cancer
2. Carcinoma(b) Excessive thirst
3. Polydipsia(c) Excessive hunger
4. Polyphagia(d) Lack of blood flow to the heart muscle
5. Myocardial Infarction(e) Connective tissue cancer

Answer:

  1. (e) Connective tissue cancer
  2. (a) Stomach cancer
  3. (b) Excessive thirst
  4. (c) Excessive hunger
  5. (d) Lack of blood flow to the heart muscle.

V. Fill in the blanks:

Question 1.
Cirrhosis is caused in the liver due to excessive use of _______.
Answer:
Alcohol.

Question 2.
A highly poisonous chemical derived from tobacco is _______.
Answer:
Nicotine.

Question 3.
Blood cancer is called _______.
Answer:
Leukaemia.

Question 4.
Less response of a drug to a specific dose with repeated use is called _______.
Answer:
Tolerance.

Question 5.
Insulin resistance is a condition in _______ diabetes mellitus.
Answer:
Type – 2.

VI. Analogy Type Questions.

Identify the first words and their relationship and suggest a suitable word for the fourth blank:

Question 1.
Communicable : AIDS :: Non – communicable : _______.
Answer:
Obesity.

Question 2.
Chemotherapy : Chemicals :: Radiation therapy : _______.
Answer:
Radiation.

Question 3.
Hypertension : Hypercholesterolemia :: Glycosuria : _______.
Answer:
Polyphagia.

VII. Answer in a Sentence.

Question 1.
What are psychotropic drugs?
Answer:
The drugs which act on the brain and alter the behaviour, consciousness, power of thinking and perception, are called Psychotropic drags. They are also called Mood altering drugs.

Question 2.
Mention the diseases caused by tobacco smoke.
Answer:
Bronchitis, pulmonary tuberculosis, emphysema hypoxia, lung cancer, hypertension gastric and duodenal ulcer are diseases caused be tobacco smoke.

Question 3.
What are the contributing factors for obesity?
Answer:
Obesity is due to genetic factors, physical inactivity, overeating and endocrine factors.

Question 4.
What is adult onset diabetes?
Answer:
Type-2 Non Insulin Dependent Diabetes Mellitus (NIDDM) is called as adult onset diabetes.

Question 5.
What is metastasis?
Answer:
The Cancerous cells migrate to distant parts of the body and affect new tissues and this process is called Metastasis.

Question 6.
How does insulin deficiency occur?
Answer:
Insulin deficiency occur due to the destruction of B – cells of the pancreas, characterized by abnormally elevated blood glucose level resulting from inadequate insulin secretion.

VIII. Short Answer Questions

Question 1.
What are the various routes by which transmission of human immunodeficiency virus takes place?
Answer:
HIV is transmitted generally by:

  1. Sexual contact with infected person
  2. Use of contaminated needles or syringes especially in case of intravenous drag abusers
  3. By transfusion of contaminated / infected blood or blood products (iv) From infected mother to her child through placenta.

Question 2.
How is a cancer cell different from a normal cell?
Answer:
Cancer is an abnormal and uncontrolled division of cells that invade and destroy the surrounding tissue, forming a tumour or neoplasm. It is a heterogeneous group of cells, that do not respond to the normal cell division. The cancer cells move to distant parts of bodies such as lungs, bones, liver, skin and brain.

Question 3.
Differentiate between Type-1 and Type-2 diabetes mellitus.
Answer:

Type-1 Diabetes mellitusType-2 Diabetes mellitus
1. People with type – 1 diabetes do not produce insulin in the pancreas.1. People with type – 2 diabetes do not respond to insulin.
2. the immune system destroys insulin – producing beta cells in the pancreas.2. People with type – 2 diabetes are Insulin Resistant. The body produces insulin but unable to use effectively.
3. Cannot be controlled without taking insulin.3. Possible to treat initially without medication or treating with tablets.

Question 4.
Why is a dietary restriction recommended for an obese individual?
Answer:
Obesity has a positive risk factor in development of hypertension, diabetes, gall bladder disease, coronary heart disease and arthritis. To avoid the dietary restriction is recommended for an obese individual.

Question 5.
What precautions can be taken for preventing heart diseases?
Answer:
Diet Management: Reduction in the intake of calories, low saturated fat and cholesterol – rich food, low carbohydrates and common salt are some of the Dietary modifications. Diet rich in polyunsaturated fatty acids is essential. Increase in the intake of fibre diet, fruits and vegetables, protein, minerals and vitamins are needed.

  • Physical activity: Regular exercise, walking and yoga are essential for bodyweight maintenance.
  • Avoid Addictive substances: Alcohol consumption, Psychotropic drugs and smoking are to be avoided.

IX. Long Answer Questions

Question 1.
Suggest measures to overcome the problems of an alcoholic.
Answer:
Education and counselling: Education and proper counselling will help the alcoholics to overcome their problems and stress, to accept failures in their life.
Physical activity : Individuals undergoing rehabilitation should be channelized into healthy activities like reading, music, sports, yoga and meditation.

Seeking help from parents and peer groups : When a problematic situation occurs, the affected individuals should seek help and guidance from parents and peers. This would help them to share their feeling of anxiety, wrong dping and get rid of the habit.

Medical assistance : Individual should seek help from psychologists and psychiatrists to get relieved from this condition and to lead a relaxed and peaceful life.

Alcohol de-addiction and rehabilitation programmes are helpful to the individual so that they could get rid of the problem completely and can lead a normal and healthy life.

Question 2.
Changes in lifestyle is a risk factor for the occurrence of cardiovascular diseases. Can it be modified? If yes, suggest measures for prevention.
Answer:
The lifestyle can be modified to prevent cardiovascular diseases. These are the measures for prevention:

  • Do not smoke or use Tobacco.
  • Do Exercise for about 30 minutes.
  • Eat a heart-healthy diet.
  • Reduce the intake of calories, low saturated fat and cholesterol, low carbohydrates and common salt are some of the dietary modifications.
  • Diet rich in polyunsaturated fatty acids (PUFA) is essential.
  • Increase in the intake of fibre diet, fruits and vegetables, protein, minerals and vitamins are essential.
  • Maintain a healthy weight.
  • Get enough quality sleep.
  • Manage stress.
  • Get regular health screens.
  • Control Blood pressure.
  • Keep the cholesterol and triglyceride levels under control.

X. Higher Order Thinking Skills (HOTS) Questions

Question 1.
What is the role of fat in the cause of atherosclerosis?
Answer:
The deposition of cholesterol in the blood vessels gradually develops from which form a fatty streak called plaque. This blocks the pathway of blood flow by narrowing the blood vessels leading to atherosclerosis.

Question 2.
Eating junk food and consuming soft drinks results in health problems like obesity, still, children prefer. What are the suggestions you would give to avoid children eating junk food / consumption of soft drinks?
Answer:
Suggestions, to avoid children, eating Junk food / consumption of soft drinks.

  • Carry a water bottle and drink water.
  • Instead of soft drinks, drink fruit juices, sports drinks or energy drinks.
  • Base meals around protein, legumes, chickpeas, kidney beans and nuts, etc.
  • Avoid getting extremely hungry.
  • Fight stress.
  • Practice mindful eating.
  • Have a piece of fruit, yoghurt, or some crackers.

Question 3.
Regular physical exercise is advisable for normal functioning of the human body. What are the advantages of practising exercise in daily life?
Answer:

  1. Physical exercises help us to live longer and prevent many chronic diseases.
  2. It improves cardiorespiratory and muscular fitness.
  3. It reduces stress, anxiety and depression and improves our mood.
  4. Improves sleep quality and overall quality of life.

Question 4.
A leading weekly magazine has recently published a survey analysis which says that a number of AIDS patient in the country is increasing day by day. The report says that the awareness among the people about AIDS is still very poor. You are discussing the magazine report in your class and a team of your class decides to help people to fight against the dreadful disease.
(a) What problem do you face when trying to educate the people in your village near your school?
(b) How do you overcome the problem?
Answer:
(a) The main problem, we face, is as follows:

  • AIDS patients find it difficult to accept the news.
  • Many people are afraid of telling others because they feel ashamed or they are worried about being rejected.
  • AIDS patients are really discouraged with anxiety about their future.

(b)

  • Confirm the disease by Western Blot Analysis or ELISA.
  • Antiretroviral drugs and immunostimulating therapy can prolong the life of the infected person.
  • Do not tell anyone about our friend’s HIV.
  • Be there to talk to them.
  • Do things together that can reduce stress. Go for a walk. Do something that we enjoy with our AIDS patient friend.
  • Advice the patient friend to avoid activities that have bad health effects like smoking.
  • Patients with HIV / AIDS should not be isolated from the family and society.

XI. Value-Based Questions

Question 1.
Once a person starts taking drugs or alcohol it is difficult to get rid of the habit. Why?
Answer:
The addictive potential of the drugs pulls the individual into a viscous cycle leading to regular abuse and depending. Moreover, some drugs act in the brain and alter the behaviour, consciousness, power of thinking and perception.

Question 2.
Men addicted to tobacco lead to oxygen deficiency in their body. What could be the possible reason?
Answer:
Carbon monoxide of tobacco smoke binds to the haemoglobin of RBC and decreases its oxygen-carrying capacity causing hypoxia in body tissues.

Question 3.
Name any three foods that are to be avoided and included in the diet of a diabetic patient. Why should it be followed?
Answer:
Refined sugar, carbohydrates rich food and high fat content rich foods should be avoided.
Low carbohydrate and fibre rich diet. Diet comprising whole grains, millet, green leafy vegetables should be included in the diet.

Question 4.
How can informational efforts change people’s HIV knowledge and behaviour?
Answer:

  • Find the latest information about viral suppression and Viral Load Monitoring.
  • Find the latest prevention and how to talk with patients with HIV about, what it means for them.
  • Learn how HIV care providers, can identify and address mental health and substance use disorders to help patients, adhere to HIV treatment and remain in care.

XII. Assertion and Reasoning Questions

In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of statements given below mark the correct answer as
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion Mid Reason is true that Reason is not the correct explanation of Assertion.
(c) The assertion is true but Reason is false.
(d) Both Assertion and Reason are false.

Question 1.
Assertion: All drugs act on the brain.
Reason: Drugs disturb the functioning of the body and mind.
Answer:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Question 2.
Assertion: Excretion of excess glucose in the urine is observed in a person with diabetes mellitus.
Reason: Pancreas is unable to produce sufficient quantity of insulin.
Answer:
(b) If both Assertion and Reason are true that Reason is not the correct explanation of Assertion.

Textbook Activities Solved

Question 1.
Collect pictures of people affected by tobacco chewing and tobacco smoking. Identify which part of the body is affected and the health hazards it can lead to?
Answer:
The students should collect pictures of people affected by Tobacco Chewing and Tobacco smoking.
Health Hazards: Affected part is mouth on Tobacco Chewing. Chewing Tobacco causes mouth cancer, throat cancer, soreness, gum diseases, tooth decay, tooth loss, possible links to other cancer and Cardiovascular diseases.

Tobacco smoking causes Lung diseases causing damaging alveoli, emphysema, chronic bronchitis, cough, cold, wheezing, asthma, pneumonia and lung cancer. It also affects the central nervous system, increases blood pressure and heartbeat. It also damages DNA.

Question 2.
Collect pictures of individuals with normal liver and alcoholic liver, compare and indicate the changes you find in them.
Answer:

  • The students should collect pictures of normal liver and alcoholic liver.
  • Normal liver: Under normal circumstances, the normal liver is smooth with no irregularities. The enzymes mostly reside within the cells of the liver.

Fatty liver disease occurs as a result of alcohol drinking, which leads to cirrhosis and formation of fibrous tissues, which replaces the normal liver tissue.

Question 3.
Prepare a chart showing the food items which are preferable and which should be avoided to prevent high blood pressure and heart disease. Apart from diet what are the other lifestyle modifications to be followed to manage this condition?
Answer:

  1. Food items which are preferable: Whole grains, fruits and vegetables, low – fat dairy products, Green tea, Hibiscus tea, Pineapple juice and low carbohydrate food items.
  2. Food items to be avoided: Salt, Meat, Pickles, Canned Soups, Tomato products, sugar, packaged foods, White bread and packaged snacks, etc.

Other Life Style Modification:

  • Exercise for about 30 minutes.
  • Eat a heart-healthy diet.
  • Do not smoke or use tobacco.
  • Get regular health screenings.
  • Get enough quality sleep.

Samacheer Kalvi 10th Science Health and Diseases

Additional Questions Solved

I. Fill in the blanks.

Question 1.
Tobacco is obtained from the Tobacco plant _____ and ______.
Answer:
Nicotiana tobacco and Nicotiana rustica.

Question 2.
The increased urine output, leading to dehydration is termed as ______.
Answer:
Polyuria.

Question 3.
The inflammation of throat and bronchi due to smoke of Tobacco lead to the conditions of _____ and ______.
Answer:
Bronchitis and Pulmonary tuberculosis.

Question 4.
The study of cancer is called ______.
Answer:
Oncology.

Question 5.
The uncontrolled division of cells destroy the surrounding tissue forming a tumour or ______.
Answer:
Neoplasm.

Question 6.
_____ and ______ hydrocarbons present in tobacco smoke is carcinogenic causing Lung cancer.
Answer:
Benzopyrene and Polycyclic.

II. Write ‘True’ or ‘False’ for the following statements. Correct the false statements:

Question 1.
The psychological dependent persons feel that drugs do not help them to reduce stress.
Answer:
False.
Correct Statement: The psychological dependent persons feel that drugs help them to reduce stress.

Question 2.
Individuals should seek help from psychologists and psychiatrists to get relief from alcohol abuse.
Answer:
True.

Question 3.
Tobacco chewing does not cause oral cancer.
Answer:
False.
Correct Statement: Tobacco chewing causes oral cancer.

Question 4.
In Type – 2 Non – Insulin Dependent Diabetes Mellitus, the target cells respond to insulin and allow the movement of glucose into cells.
Answer:
False.
Correct Statement: In Type – 2 Non – Insulin Dependent Diabetes Mellitus, the target cells do not respond to insulin and does not allow the movement of glucose into cells.

Question 5.
Low Carbohydrate food in the form of starch, complex sugars, and fibre-rich diets are more appropriate for the Dietary management pf Diabetes.
Answer:
True.

III. Expand the following abbreviations:

Question 1.

  1. CVD
  2. HDL
  3. PUFA
  4. NACO
  5. NGO
  6. ELISA
  7. WHO
  8. NCPCR
  9. CPCR
  10. LOL
  11. UV rays.

Answer:

  1. Cardio-vascular Disease
  2. High-Density Lipoprotein
  3. Polyunsaturated Fatty Acids
  4. National AIDS Control Organization
  5. Non-Government Organization
  6. Enzyme-Linked ImmunoSorbent Assay
  7. World Health Organization
  8. National Commission for Protection of Child Rights
  9. Commission for Protection of Child Rights
  10. Low-Density Lipoprotein
  11. Ultra Violet rays.

IV. Match the following:

Question 1.

1. Psychotropic drugs(a) Nicotine
2. Chronic metabolic disorder(b) Emphysema
3. Addiction to Tobacco(c) Polyphagia
4. Excess hunger(d) Polydipsia
5. Inflammation of lung alveoli(e) Mood Altering drugs
6. Loss of water leads to thirst(f) Diabetes Mellitus

Answer:

  1. (e) Mood Altering drugs
  2. (f) Diabetes Mellitus
  3. (a) Nicotine
  4. (c) Polyphagia
  5. (b) Emphysema
  6. (d) Polydipsia.

V. Choose the correct answer.

Question 1.
When powdered tobacco is taken through the nose, it is called ______.
(a) smoking
(b) stimulant
(c) snuffing
(d) addiction.
Answer:
(c) snuffing

Question 2.
Causative factor of cancer is called:
(a) Oncogenes
(b) Radiogenes
(c) Oestrogenes
(d) Carcinogens
Answer:
(d) Carcinogens

Question 3.
Insulin deficiency due to the destruction of β – cells occur in ______.
(a) IDDM
(b) BMI
(c) NIDDM
(d) CVD.
Answer:
(a) IDDM

Question 4.
Which is not cancer?
(a) Leukaemia
(b) Glaucoma
(c) Sarcoma
(d) Carcinogen
Answer:
(b) Glaucoma

Question 5.
The HIV Virus attack the body’s disease – fighting mechanism and the individual is prone to infectious diseases.
(a) Erythrocytes
(b) Thrombocytes
(c) Lymphocytes
(d) platelets.
Answer:
(c) Lymphocytes

VI. Write the correct dates for the following:

Question 1.

  1. December 1st
  2. 4th February
  3. 7th November
  4. May 31st
  5. June 26th.

Answer:

  1. World AIDS Day
  2. World Cancer day
  3. National Cancer awareness day
  4. No Tobacco Day or World Anti-Tobacco day
  5. International day against Drug abuse and Illicit Trafficking.

VII. Answer the following briefly:

Question 1.
What are stimulants?
Answer:
Drugs that increase the activities of Central Nervous System.

Question 2.
What is abuse? What does it include?
Answer:
Abuse refers to cruel, violent, harmful or injurious treatment of another human being. It includes physical, emotional or psychological, verbal, child and sexual abuses.

Question 3.
List the instruction to be given to prevent child sexual abuse.
Answer:

  1. Do not talk to any suspected person or strangers and to maintain a distance.
  2. Not to be alone with unknown person.
  3. To be careful while travelling alone in public or private transport:
  4. Not to receive money, toys, gifts or chocolates from known or unknown person to them without the knowledge of their parents.
  5. Not to allow known or unknown person to touch them.

Question 4.
What is an addiction? What is the effect of addiction on individuals?
Answer:
The physical and mental dependency on – alcohol, smoking and drugs are called addiction. The addictive potential of these substances pulls an individual into a vicious cycle leading to regular abuse and dependency.

Question 5.
What are the symptoms of diabetes?
Answer:
Diabetes mellitus is associated with several metabolic alterations. The most important symptoms are

  1. Increased blood glucose level (Hyperglycemia).
  2. Increased urine output (Polyuria) leading to dehydration.
  3. Loss of water leads to thirst (Polydipsia) resulting in increased fluid intake.
  4. Excessive glucose excreted in urine (Glycosuria).
  5. Excess hunger (Polyphagia) due to loss of glucose in urine.
  6. Fatigue and loss of weight.

Question 6.
Explain the types of cancers on the basis of the tissues from which they are formed?
Answer:
Cancers are classified on the basis of the tissues, from which they are formed:

  • Carcinomas arise from epithelial and glandular tissues.
  • Sarcomas occur in connective and muscular tissue. They include the cancer of bones, cartilage, tendons, adipose tissue and muscles.
  • Leukaemia is characterised by an increase in the formation of white blood cells in the bone marrow and lymph nodes Leukaemia is called blood cancers.

Question 7.
Name the test done to diagnosis Aids.
Answer:
The presence of HIV virus can be confirmed by western Blot analysis or Enzyme Linked Immunosorbent Assay (ELISA)

Question 8.
What is the treatment of cancer and the preventive measures for cancer?
Answer:
The treatment of cancer involves the following methods:

  • Surgery: Tumours are removed by surgery to prevent further spread of cancer cells.
  • Radiation therapy: Tumour cells are irradiated by lethal doses of radiation while protecting the surrounding normal cells.
  • Chemotherapy: It involves the administration of anticancerous drugs, which prevent cell division and are used to kill cancer cells.
  • Immunotherapy: Biological response modifiers like interferons are used to activate the immune system and help in destroying the tumours.

Preventive measures for cancer:

  • Cancer control programmes should focus on primary prevention and early detection.
  • To prevent lung cancer, tobacco smoking is to be avoided.
  • Protective measures to be taken against exposure to toxic pollutants of industries.
  • Excessive exposure to radiation is to be avoided to prevent skin cancer.

Question 9.
Explain the symptoms and treatment of AIDS.
Answer:

  • Infected individuals become immunodeficient.
  • The person becomes more susceptible to viral, bacterial, protozoan and fungal diseases.
  • Swelling of lymph nodes, damage to the brain, loss of memory, lack of appetite and weight loss, fever, chronic diarrhoea, cough, lethargy, pharyngitis, nausea and headache.

1. Diagnosis: The presence of the HIV virus can be detected by Western Blot Analysis or Enzyme – Linked ImmunoSorbent Assay (ELISA).
2. Treatment: Anti – retroviral drugs and immunostimulating therapy can prolong the life of the infected person.

Question 10.
Briefly note down the prevention and control of AIDS.
Answer:
The following steps help in controlling and preventing the spreading of HIV:

  • Screening of blood from blood banks for HIV, before transfusion.
  • Ensuring the use of disposable needles and syringes in hospitals and clinics.
  • Advocating safe sex and the advantages of using condoms.
  • Creating an awareness campaign and educating people on the consequences of AIDS.
  • Persons with HIV / AIDS should not be isolated from the family and society.

Question 11.
What is obesity and body mass Index?
Answer:
Obesity is the state in which there is an accumulation of excess body fat with an abnormal increase in body weight.
Body Mass Index (BMI) is an estimate of body fat and health risk.
BMI = Weight (kg) / Height (m)2

Question 12.
What are the major causes and contributing factors for heart disease?
Answer:
Hypercholesterolemia (High blood cholesterol) and high blood pressure (Hypertension) are the major causes and contributing factors for heart disease.

  1. Heredity (family history)
  2. Diet rich in saturated fat and cholesterol
  3. Obesity, increasing age
  4. Cigarette smoking
  5. Emotional stress
  6. Sedentary lifestyle
  7. Excessive alcohol consumption and
  8. Physical inactivity are some of the causes.

VIII. Identify the first words and their relationship and suggest a suitable word for the fourth blank:

Question 1.
Drug abuse : addictive drug :: Tobacco chewing : ______.
Answer:
Oral cancer or mouth cancer.

Question 2.
Insulin : Diabetes :: Benzopyrene : ______.
Answer:
Lung cancer.

Question 3.
Disease of heart and blood vessels : Cardiovascular disease :: Deposition of cholesterol in the blood vessel : ______.
Answer:
Coronary Heart Disease (CHD).

Question 4.
Deficient blood supply to heart muscle : Ischemia :: Death of the heart muscle tissue : ______.
Answer:
Myocardial Infarction.

Question 5.
HIV Virus : ELISA :: Leukaemia : ______.
Answer:
Blood cancer.

X. Explain the following in detail.

Question 1.
Explain the approaches for protection of an abused child and the prevention of child sexual abuse.
Answer:

  • Child helpline: The Child Helpline provides a social worker who can assist the child by providing food, shelter and protection.
  • Counselling the child: Psychologists and social workers should provide guidance, counselling and continous support to a victim child.
  • Family support: The victimized child should be supported by the family members. They should provide proper care and attention to child to overcome his/her sufferings.
  • Medical care: A child victim of sexual offences should receive medical care and treatment from health care professionals to overcome mental stress and depression.
  • Legal Counsel: The family or the guardian of the child victim shall be entitled to free assistance of a legal counsel for such offence.
  • Rehabilitation: Enrolling in schools and resuming their education is an important step towards the rehabilitation of the child.
  • Community – based efforts: Conducting awareness campaign on child abuse and its prevention.

Question 2.
List out the harmful effects of Alcohol to health.
Answer:
Prolonged use of alcohol depresses the nervous system, by acting as a sedative and analgesic substance. Some of the harmful effects are:

  1. Nerve cell damage resulting in various mental and physical disturbances.
  2. Lack of co-ordination of body organs.
  3. Blurred or reduced vision, results in road accidents.
  4. Dilation of blood vessels which may affect functioning of the heart.
  5. Liver damage resulting in fatty liver which leads to cirrhosis and formation of fibrous tissues.
  6. Body loses its control and consciousness eventually leading to health complications and ultimately to death.

Question 3.
Explain in detail the Smoking Hazards and effects of Tobacco. How can it be prevented?
Answer:
When smoke is inhaled, the chemicals get absorbed by the tissues and cause the following harmful effects:

  • Benzopyrene and polycyclic hydrocarbons present in Tobacco smoke are carcinogenic causing lung cancer.
  • Causes inflammation of throat and bronchi leading to conditions like bronchitis and pulmonary tuberculosis.
  • Inflammation of lung alveoli, decrease surface area for gas exchange and cause emphysema.
  • Carbon monoxide of Tobacco smoke binds to the haemoglobin of RBC and decreases its oxygen-carrying capacity causing hypoxia in body tissues.
  • Increased blood pressure caused by smoking leads to increased risk of heart disease.
  • Causes increased gastric secretion which leads to gastric and duodenal ulcers.
  • Tobacco chewing causes oral cancer (mouth cancer).

Prevention: Adolescents and old people need to avoid these habits. Proper counselling and medical assistance can help an addict to give up the habit of smoking.

XI. Higher Order Thinking Skills (HOTS) Questions

Question 1.
What do the following symbols represent?

Answer:
(a) 1. No Smoking
2. No Alcohol
3. No Psychotropic drugs
(b) 4. No – International Tobacco day
5. Inflammation of Lung Alveoli and decreased surface area.

Question 2.
Some human diseases are transmitted only through blood in one of such diseases, there is a progressive decrease in the number of lymphocytes of the patient.
(a) Name the disease and its causative agent.
(b) Write any two symptoms of it.
Answer:
(a) Name the disease is the AIDS caused by Human Immuno Deficiency Virus.
(b) Weight loss and lack of appetite are the symptoms of AIDS.

Question 3.
Which is the desirable blood cholesterol level for Indians?
Answer:
200 mg / dl.

Question 4.
Which cholesterol lowers the risk of heart disease and which cholesterol increases the risk of heart diseases?
Answer:

  • HDL (High – Density Lipoprotein) or good cholesterol lowers the risk of heart disease.
  • LDL (Low – Density Lipoprotein) or bad cholesterol increases the risk of heart diseases.

Question 5.
What are the two types of tumours?
Answer:

  • Benign tumours or Non – malignant tumours: Remain confined in the organ affected and do not spread to other parts of the body.
  • Malignant tumours: Mass of proliferating cells, which grow very rapidly invading and damaging the surrounding normal tissues.

Question 6.
Name some foods which help to reduce blood sugar levels.
Answer:
Flax seeds containing insoluble fibre, Guava, Tomatoes and spinach are the foods, which helps to reduce blood sugar levels.


Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 20, Breeding and Biotechnology, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
Which method of crop improvement can be practised by a farmer if he is inexperienced?
(a) clonal selection
(b) mass selection
(c) pure line selection
(d) hybridisation.
Answer:
(a) clonal selection

Question 2.
Pusa Komai is a disease resistant variety of:
(a) sugarcane
(b) rice
(c) cow pea
(d) maize
Answer:
(c) cow pea

Question 3.
Himgiri developed by hybridisation and selection for disease resistance against rust pathogens is a variety of ______.
(a) chilli
(b) maize
(c) sugarcane
(d) wheat.
Answer:
(d) wheat.

Question 4.
The miracle rice which saved millions of lives and celebrated its 50th birthday is:
(a) IR 8
(b) IR 24
(c) Atomita 2
(d) Ponni
Answer:
(a) IR 8

Question 5.
Which of the following is used to produce products useful to humans by biotechnology techniques?
(a) enzyme from organism
(b) live organism
(c) vitamins
(d) both (a) and (b).
Answer:
(d) both (a) and (b).

Question 6.
We can cut the DNA with the help of:
(a) scissors
(b) restriction endonucleases
(c) knife
(d) RNAase
Answer:
(b) restriction endonucleases

Question 7.
rDNA is a ______.
(a) vector DNA
(b) circular DNA
(c) recombinant of vector DNA and desired DNA
(d) satellite DNA.
Answer:
(c) recombinant of vector DNA and desired DNA

Question 8.
DNA fingerprinting is based on the principle of identifying sequences of DNA:
(a) single-stranded
(b) mutated
(c) polymorphic
(d) repetitive
Answer:
(d) repetitive

Question 9.
Organisms with a modified endogenous gene or a foreign gene are also known as ______.
(a) transgenic organisms
(b) genetically modified
(c) mutated
(d) both (a) and (b).
Answer:
(a) transgenic organisms

Question 10.
In hexaploid wheat (2n = 6x = 42) the haploid (n) and the basic(x) number of chromosomes are:
(a) n = 7 and x = 21
(b) n = 21 and x = 21
(c) n = 1 and x = 1
(d) n = 21 and x = 7
Answer:
(d) n = 21 and x = 7

II Fill in the blanks.

Question 1.
Economically important crop plants with superior quality are raised by ______.
Answer:
Breeding.

Question 2.
A protein rich wheat variety is ______.
Answer:
Atlas 66.

Question 3.
_______ is the chemical used for doubling the chromosomes.
Answer:
Colchicine.

Question 4.
The scientific process which produces crop plants enriched with desirable nutrients is called ______.
Answer:
Biofortification.

Question 5.
Rice normally grows well in alluvial soil, but _____ is a rice variety produced by mutation breeding that grows well in saline soil.
Answer:
Atomita – 2 rice

Question 6.
_____ technique made it possible to genetically engineer living organism.
Answer:
Recombinant DNA.

Question 7.
Restriction endonucleases cut the DNA molecule at specific positions known as ______.
Answer:
Molecular scissors.

Question 8.
Similar DNA fingerprinting is obtained for ______.
Answer:
Identical twins.

Question 9.
______ cells are undifferentiated mass of cells.
Answer:
Pleuripotent.

Question 10.
In gene cloning, the DNA of interest is integrated in a ______.
Answer:
Vector [plasmid].

III. State whether true or false. If false, write the correct statement.

Question 1.
Raphano brassica is a man – made tetraploid produced by colchicine treatment.
Answer:
True.

Question 2.
The process of producing an organism with more than two sets of chromosome is called mutation.
Answer:
False.
Correct statement: The process of producing an organism with more than two sets of chromosome is called polyploidy.

Question 3.
A group of plants produced from a single plant through vegetative or asexual reproduction are called a pureline.
Answer:
False.
Correct statement: A group of plants produced from a single plant through vegetative or asexual reproduction are called clones.

Question 4.
Iron fortified rice variety determines the protein quality of the cultivated plant.
Answer:
False.
Correct statement: Iron fortified rice variety determines the iron quality of the cultivated plant.

Question 5.
Golden rice is a hybrid.
Answer:
False.
Correct statement: Golden rice is a genetically modified plant.

Question 6.
Bt gene from bacteria can kill insects.
Answer:
True.

Question 7.
In vitro fertilisation means the fertilisation done inside the body.
Answer:
False.
Correct statement: In vitro fertilisation means the fertilisation done outside the body.

Question 8.
DNA fingerprinting technique was developed by Alec Jeffrey.
Answer:
True.

Question 9.
Molecular scissors refers to DNA ligases.
Answer:
False.
Correct statement: Molecular scissors refers to Restriction Enzymes.

IV. Match the following:

Question 1.

Column AColumn B
1. Sonalika(a) Phaseolus mungo
2. IR-8(b) Sugarcane
3. Saccharum(c) Semi-dwarf wheat
4. Mung No. 1(d) Groundnut
5. TMV-2(e) Semi-dwarf Rice
6. Insulin(f) Bacillus thuringienesis
7. Bt toxin(g) Beta carotene
8. Golden rice(h) the first hormone produced using rDNA technique

Answer:

  1. (c) Semi – dwarf wheat
  2. (e) Semi – dwarf Rice
  3. (b) Sugarcane
  4. (a) Phaseolus mungo
  5. (d) Groundnut
  6. (h) the first hormone produced using rDNA technique
  7. (f) Bacillus thuringienesis
  8. (g) Beta carotene.

V. Understand the assertion statement, justify the reason given and choose the correct choice:

(a) The assertion is correct and the reason is wrong.
(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason are correct.
(d) Both assertion and reason are wrong.

Question 1.
Assertion: Hybrid is superior to either of its parents.
Reason: Hybrid vigour is lost upon inbreeding.
Answer:
(a) The assertion is correct and the reason is wrong.

Question 2.
Assertion: Colchicine reduces the chromosome number.
Reason: It promotes the movement of sister chromatids to the opposite poles.
Answer:
(d) Both assertion and reason are wrong.

Question 3.
Assertion: rDNA is superior over hybridisation techniques.
Reason: Desired genes are inserted without introducing the undesirable genes in target organisms.
Answer:
(c) Both assertion and reason are correct.

VI. Answer in a Sentence

Question 1.
Give the name of the wheat variety having higher dietary fibre and protein.
Answer:
Atlas 66, a protein-rich variety, having higher dietary fibre and protein.

Question 2.
Semi-dwarf varieties were introduced in rice. This was made possible by the presence of dwarfing gene in rice. Name this dwarfing gene.
Answer:
Dee-geo-woo-gen a dwarf variety from China.

Question 3.
Define genetic engineering.
Answer:
Genetic engineering is the manipulation and transfer of genes from one organism to another organism to create a new DNA called recombinant DNA (rDNA). Genetic engineering is also called recombinant DNA technology.

Question 4.
Name the types of stem cells.
Answer:
Embryonic stem cells and somatic stem cells are the types of stem cells.

Question 5.
What are transgenic organisms?
Answer:
Plants or animals expressing a modified endogenous gene or a foreign gene are called transgenic organisms.

Question 6.
State the importance of biofertiliser.
Answer:
Biofertilizer adds nutrients through the natural process of nitrogen fixation, stimulate the plant growth through the synthesis of growth-promoting substance.

VII. Short Answer Questions

Question 1.
Discuss the method of breeding for disease resistance.
Answer:
Plant diseases are caused by pathogens like viruses, bacteria and fungi. This affects crop yield. To develop disease-resistant varieties of crops, that would increase the yield and reduce the use of fungicides and bactericides are important. Some disease-resistant varieties are as follows:

CropVarietyResistance to diseases
WheatHimgiriLeaf and stripe rust, hill bunt
CauliflowerPusa Shubhra, Pusa Snowball K-1Black rot
CowpeaPusa KomalBacterial blight

Question 2.
Name three improved characteristics of wheat that helped India to achieve high productivity.
Answer:
Sonalika, kalyan and sona are the three improved characteristic of wheat that helped India to achieve high productivity.

Question 3.
Name two maize hybrids rich in amino acid lysine.
Answer:
Protina, Shakti and Rathna are lysine – rich maize hybrids, which are developed in India.

Question 4.
Distinguish between
(a) Somatic gene therapy and germline gene therapy.
(b) Undifferentiated cells and differentiated cells.
Answer:
(a) Somatic gene therapy and germline gene therapy.

Somatic gene therapyGermline gene therapy
Somatic gene therapy is the replacement of the defective gene in somatic cells.Germline gene therapy is the replacement of the defective gene in the germ cell (egg and sperm).

(b) Undifferentiated cells and differentiated cells.

Undifferentiated cellsDifferentiated cells
Our body is composed of over 200 specialised cell types, that can carry out specific functions, eg. Neurons or nerve cells that can transmit signals. Pancreatic cells to secrete insulin. These specialised cells are called as differentiated cells.The cells which are variable potency, undifferentiated or unspecialised mass of cells are called stem cells. The stem cells are undifferentiated or unspecialised mass of cells.

Question 5.
State the applications of DNA fingerprinting technique.
Answer:
Applications of DNA Fingerprinting:
(i) DNA fingerprinting technique is widely used in forensic applications like crime investigation such as identifying the culprit. It is also used for paternity testing in case of disputes.
(ii) It also helps in the study of genetic diversity of population, evolution and speciation.

Question 6.
How are stem cells useful in the regenerative process?
Answer:
Sometimes cells, tissues and organs in the body may be permanently damaged or lost due to genetic condition or disease or injury. In such situations, stem cells are used for the treatment of diseases, which is called stem – cell therapy. In treating neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease neuronal stem cells can be used to replace the damaged or lost neurons.

Question 7.
Differentiate between outbreeding and inbreeding.
Answer:
Inbreeding:
When breeding or mating takes place between animals of the same breed, for about 4 – 6 generations, then it is called inbreeding. Superior males and superior females of the same breed are identified and mated in pairs. It helps in the accumulation of superior genes and the elimination of undesirable genes. Inbreeding depression is the continued inbreeding, which reduces fertility and productivity. Inbreeding exposes harmful recessive genes that are eliminated by selection.

Outbreeding:
The breeding of unrelated animals is outbreeding. The offsprings formed are called hybrids. The hybrids are stronger and vigorous than their parents. Cross between two different species with desirable features of economic value is mated. Mule is superior to the horse in strength, intelligence, ability to work and resistance to diseases, but they are sterile.

VIII. Long Answer Questions

Question 1.
What are the effects of hybrid vigour in animals.
Answer:

  1. Increased production of milk by cattle.
  2. Increased production of egg by poultry.
  3. High quality of meat is produced.
  4. Increased growth rate in domesticated animals.

Question 2.
Describe mutation breeding with an example.
Answer:
The mutation is defined as the sudden heritable change in the nucleotide sequence of DNA in an organism. The genetic variations brings out changes in an organism. The organism which undergoes mutation is called a mutant.
The factors which induce mutations are known as mutagens or mutagenic agents. The mutagens are of two types:
(a) Physical mutagens: Radiations like X – rays, a, P and Y – rays, UV rays and temperature, etc, which induce, maturations are called physical mutagens.

(b) Chemical mutagens: Chemical substances that induce mutations are called chemical mutagens, eg. Mustard gas and nitrous acid. The utilization of induced mutation in crop improvement is called mutation inbreeding.
Achievements of mutation breeding:

  • Sharbati Sonora wheat produced from Sonora – 64 by using gamma rays.
  • Atomica – 2 rice with saline tolerance and pest resistance.
  • Groundnuts with thick shells.

Question 3.
Biofortification may help in removing hidden hunger. How?
Answer:
Biofortification: Biofortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals. Some examples of crop varieties developed as a result of biofortification are given below:

  1. Protina, Shakti and Rathna are lysine rich maize hybrids (developed in India).
  2. Atlas 66, a protein rich wheat variety.
  3. Iron rich fortified rice variety’.
  4. Vitamin A enriched carrots, pumpkin and spinach.

Question 4.
With a neat labelled diagram explain the techniques involved in gene cloning.
Answer:
The carbon copy or more appropriately, a clone means to make a genetically exact copy of an organism. ‘Dolly’ is the cloned sheep.

In gene cloning, a gene or a piece of DNA fragment is inserted into a bacterial cell, where DNA will be multiplied (copied) as the cell divides.
The basic steps involved in gene cloning are:

  • Isolation of desired DNA fragment by using restriction enzymes.
  • Insertion of the DNA fragment into a suitable vector (plasmid) to make rDNA.
  • Transfer of rDNA into the bacterial host cell (Transformation).
  • Selection and multiplication of the recombinant host cell to get a clone.
  • Expression of the cloned gene in the host cell.

Using this strategy several enzymes, hormones and vaccines can be produced.

Question 5.
Discuss the importance of biotechnology in the field of medicine.
Answer:
Using genetic engineering techniques medicinally important valuable proteins or polypeptides that form the potential pharmaceutical products for the treatment of various diseases have been developed on a commercial scale.
Pharmaceutical products developed by rDNA technique:

  1. Insulin used in the treatment of diabetes.
  2. Human growth hormone used for treating children with growth deficiencies.
  3. Blood clotting factors are developed to treat haemophilia.
  4. Tissue plasminogen activator is used to dissolve blood clots and prevent heart attack.
  5. Development of vaccines against various diseases like Hepatitis B and rabies.

IX. Higher Order Thinking Skills (HOTS) Questions

Question 1.
A breeder wishes to incorporate desirable characters into the crop plants. Prepare a list of characters he will incorporate.
Answer:
The list of character he will incorporate are:

  1. High yielding and better quantity
  2. Disease resistance
  3. Insects pest resistance
  4. Improved nutritional quality
  5. Short duration

Question 2.
Organic farming is better than Green Revolution. Give reasons.
Answer:

  • Dwarfness is desired in cereals, so fewer nutrients are consumed by the crops.
  • Fertilizer is responsive.
  • Disease resistant varieties.
  • Insect and pest resistant crop varieties.
  • High levels of desirable nutrients like vitamins, proteins and minerals.

Question 3.
Polyploids are characterised by gigantism. Justify your answer.
Answer:
An organism having more than two set of chromosome is called polyploidy. It can be induced by physical agents such as heat or cold treatment, X-rays and chemical agents like colchicine. As organisms produced by polyploidy have more than two set of chromosomes they are gigantic.

Question 4.
‘P’ is a gene required for the synthesis of vitamin A. It is integrated with the genome of ‘Q’ to produce genetically modified plant ‘R’.
(i) What is P, Q and R?
(ii) State the importance of ‘R’ in India.
Answer:
(i)  The P, Q and R:

  • P – Beta – carotene gene.
  • Q – Prevent vitamin A deficiency.
  • R – Golden rice.

(ii) Importance of rice in India:

  • Rice is the most important staple food for millions of people in developing countries like India.
  • Beta – carotene is produced in the endosperm of the grain. It could control the chronic health problems caused by vitamin A deficiency, especially among the poor in developing countries like India.

Samacheer Kalvi 10th Science Breeding and Biotechnology

Additional Questions Solved

I. Fill in the blanks.

Question 1.
Plant ______ is the art of developing economically important plants.
Answer:
Breeding.

Question 2.
Plant diseases are caused by ______ like viruses, bacteria and fungi.
Answer:
Pathogen.

Question 3.
______ is the first man – made cereal hybrid.
Answer:
Triticale.

Question 4.
The superiority of the hybrid obtained by cross-breeding is called _____ or ______.
Answer:
Heterosis
or
Hybrid vigour.

Question 5.
The other name for genetic engineering is ______.
Answer:
Recombinant DNA technology.

Question 6.
The organism which undergoes mutation is called a ______ and the factors which induce mutations are ______.
Answer:
Mutant; mutagenic agents.

Question 7.
The replacement of the defective gene in a germ cell (egg or sperm) is called ______.
Answer:
Germline gene therapy.

Question 8.
Blood clotting factors are developed to treat ______.
Answer:
Haemophilia.

Question 9.
Stem cells, which are undifferentiated or unspecialised mass of cells can be used for the treatment is called ______.
Answer:
Stem cell therapy.

Question 10.
_______ is used in the treatment of diabetes.
Answer:
Insulin.

II. Match the following:

Question 1.

1. Cowpea(a) Joining the DNA fragments
2. UV rays(b) New breed of sheep
3. Lady’s finger(c) Bacterial blight
4. DNA ligase(d) Flat bean
5. Pusasem 3(e) Pusa Sawani
6. Hissardale(f) Induce mutation

Answer:
1. (c) Bacterial blight
2. (f) Induce mutation
3. (e) Pusa Sawani
4. (a) Joining the DNA fragments
5. (d) Flat bean
6. (b) New breed of sheep.

III. Write “True or False” statements. Correct the false statements:

Question 1.
Modem Agricultural practices are activities carried out to improve the plants.
Answer:
True.

Question 2.
When breeding takes place between animals of the same breed, it is called outbreeding.
Answer:
False.
Correct statement: When breeding takes place between animals of the same breed, it is called inbreeding.

Question 3.
The process of introducing high yielding varieties of plants from one place to another is called a selection.
Answer:
False.
Correct statement: The process of introducing high yielding varieties of plants from one place to another is called Exotic species.

Question 4.
The mutation is a sudden inheritable change in the nucleus sequence of DNA in an organism.
Answer:
False.
Correct statement: Mutation is a sudden heritable change in the nucleotide sequence of DNA in an organism.

Question 5.
A breed is a group of animals of common origin within a species, which has certain characters, that are not found in other members of the same species.
Answer:
True.

IV. Choose the correct answer.

Question 1.
The high yielding rice variety from Indonesia and China are ______.
(a) Peta and DGWG
(b) IR-8 and Gold rice
(c) Hexaploid Triticale and Triticum durum
(d) Sonalika and Kalyan Sona.
Answer:
(a) Peta and DGWG

Question 2.
First artificially synthesized hormone is:
(a) Secretin
(b) Insulin
(c) Glucagon
(d) Renin
Answer:
(b) Insulin

Question 3.
The presence of this substance in bacteria can undergo replication independently along with chromosomal DNA ______.
(a) heritable
(b) colchicine
(c) mutation
(d) plasmid.
Answer:
(d) plasmid.

Question 4.
Bacillus thuringiensis (Bt) stains have been used for designing novel.
(a) Bio-metallogical techniques
(b) Bio-insecticidal plants
(c) Bio-mineralization
(d) Bio-fertilizer
Answer:
(b) Bio-insecticidal plants

Question 5.
A group of plants produced from a single plant through vegetative or asexual reproduction is called ______.
(a) Transgenic
(b) Hexaploid
(c) clones
(d) mutation.
Answer:
(b) Hexaploid

V. Answer the following briefly:

Question 1.
What is the green revolution? Who is the “Father of Green Revolution”?
Answer:
Green Revolution is the process of increasing food production through high yielding crop varieties and modem agricultural techniques in underdeveloped and developing nations. Dr Norman. E. Borlaug, an American agronomist is the “Father of Green Revolution”.

Question 2.
Write the role of polyploidy in crop improvement.
Answer:
The role of polyploidy in crop improvement are production of:

  1. Seedless watermelons (3n) and bananas (3n).
  2. TV-29 (triploid variety of tea) with larger shoots and drought tolerance.
  3. Triticale (6n) is a hybrid of wheat and rye. To make this plant fertile polyploidy is induced. It has higher dietary fibre and protein.
  4. Raphanobrassica is an allotetraploid by colchicine treatment.

Question 3.
What is Bio – fortification? Give any two examples.
Answer:
Bio – fortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals.
Examples of crop varieties developed as a result of bio – fortification are:

  • Protina, Shakti and Rathna are lysine – rich maize hybrids.
  • Atlas 66, A protein – rich wheat variety.

Question 4.
Give two examples of cross-breeding in animals.
Answer:
Cross breed of fowls: White Leghorn X Plymouth Rock

Hybrid fowl – yield more eggs

Cross breed of cows : Developed by mating the bulls of exotic breeds and cows of indigenous breeds.
Brown Swiss X Sahiwal

Karan Swiss – yield 2-3 times more milk than indigenous cows.

Question 5.
What is hybridization? Explain the hybridization experiment.
Answer:
The process of crossing two or more types of plants for bringing their desired characters together into one progeny hybrid is called hybridization. Hybridization is creating a genetic variation to get improved varieties.

Hybridization Experiment:
Triticale is the first man-made cereal hybrid. It is obtained by crossing wheat (Triticum durum, 2n = 28) and rye (Secale cereal, 2n = 14). The F, a hybrid is sterile (2n = 21). Then the chromosome number is doubled using colchicine and it becomes hexaploid triticale (2n = 42). The cycle of crop raising and selection continues until the plants with the desired characters are finally obtained.

Question 6.
Name the methods of plant breeding for crop improvement.
Answer:
The methods of plant breeding to develop high yielding varieties, for crop improvement, are as follows:

  • Introduction of new varieties of plants
  • Selection
  • Polyploid breeding
  • Mutation breeding
  • Hybridization.

Question 7.
Explain briefly about gene therapy.
Answer:
The replacement of a defective gene by the direct transfer of functional genes into humans to treat genetic disease or disorder is referred to as gene therapy.
The recombinant DNA technology is used for gene therapy:

  • Somatic gene therapy is the replacement of the defective gene in somatic cells.
  • Gene line gene therapy is the replacement of the defective gene in the germ cell (egg or sperm).

Question 8.
What were the important discoveries that led to the stepping stones of recombinant DNA technology?
Answer:

  1. Presence of plasmid in bacteria that can undergo replication independently along with chromosomal DNA.
  2. Restriction enzymes cuts or break DNA at specific sites and are also called as molecular scissors.
  3. DNA ligases are the enzymes which help in ligating (joining) the broken DNA fragments.

Question 9.
What does modern agriculture include?
Answer:
Modem agricultural practices are activities carried out to improve the cultivation of plants. It includes:

  1. Preparation of soil
  2. Sowing
  3. Application of manures and fertilizers
  4. Proper irrigation
  5. Protection from weeds and pests
  6. Harvesting and threshing
  7. Storage

Question 10.
What is the aim of crop improvement?
Answer:
The aim of crop improvement is to develop improved crop varieties possessing higher yield, better quality, resistance to diseases and shorter duration.

Question 11.
(a) What are the two important properties of stem cells?
(b) Write a short note on two types of stem cells.
Answer:
(a) Properties of stem cells:
It’s the ability to divide and give rise to more stem cells by self-renewal.
It’s the ability to give rise to specialised cells with specific functions by the process of differentiation.

(b) Types of cells:

  • Embryonic stem cells: Embryonic stem cells are derived from the inner cell mass of the blastocyst, which can be extracted from the early embryos. These cells can be developed into any cell in the body.
  • Adult stem cell or somatic stem cell: These cells are found in the newborn and adults. They have the ability to divide and give rise to specific cell types. Sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.

Question 12.
What are bulk genomic DNA and satellite DNA?
Answer:
In human beings, 99 % of the DNA base sequences are the same and this is called a bulk genomic DNA. The remaining 1 % of the DNA sequence differs from one individual to another. This 1 % DNA sequence is present as a small stretch of repeated sequences, which is called satellite DNA.

VI. Answer the following in detail.

Question 1.
What are stem cells? Explain its types.
Answer:
Stem cells are undifferentiated or unspecialised mass of cells. The stem cells are the cells of variable potency. The two important properties of stem cells that differentiate them from other cells are:

  1. Its ability to divide and give rise to more stem cells by self-renewal.
  2. Its ability to give rise to specialised cells with specific functions by the process of differentiation.

Types of stem cells Embryonic stem cells can be extracted and cultured from the early embryos. These cells are derived from the inner cell mass of the blastocyst. These cells can be developed into air, cell in the body.

Adult stem cell or somatic stem cell are found in the neonatal (new bom) and adults. They have tne ability to divide and give rise to specific cell types. Sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.

Question 2.
Explain with examples the inbreeding and outbreeding of animal breeding.
Answer:
Animal breeding aims at the genotypes of domesticated animals to increase their yield and improve the desirable qualities to produce milk, egg and meat. When breeding takes place between animals of the same breed, it is called inbreeding.
The cross between different – breeds is called outbreeding.

1. Inbreeding:
Inbreeding refers to the mating of closely related animals within the same breed for about 4 – 6 generations. Superior males and superior females of the same breed are identified and mated in pairs. It helps in the accumulation of superior genes and elimination of genes, which are undesirable. Hissardale is a new breed of sheep developed in Punjab by crossing Bikaneri (Magra) ewes and Australian Marino rams.

2. Inbreeding depression:
Continued inbreeding reduces fertility and productivity. Inbreeding exposes harmful recessive genes that are eliminated by selection.

3. Outbreeding:
It is the breeding of unrelated animals. The offsprings formed are called hybrids. The hybrids are stronger and vigorous than their parents. Cross between two different species with desirable features of economic value are mated. Let’s see what cross produce a mule. Mule is superior to a horse in strength, intelligence, ability to work and resistance to diseases but they are sterile

Question 3.
Explain the DNA fingerprinting technology with an illustration.
Answer:
The DNA pattern of two individuals cannot be the same except for identical twins. Each persons DNA sequence is unique, due to the small difference in the base pairs. DNA fingerprinting is the easier and quicker method, to compare the genetic difference among the two individuals. This technique was developed by Alec Jeffrey.

Each individual’s unique DNA sequences provides distinct characteristics of an individual, which helps in identification. A variable number of tandem repeat sequences [VNTRs] serve as molecular markers for identification.

In human beings, 99 % of DNA base sequences are the same and this is called as bulk genomic DNA. The remaining 1 % DNA sequence differs from one individual to another. This 1 % DNA sequence is present as a small stretch of repeated sequences which is called as satellite DNA. The number of copies of the repeat sequence also called VNTRs differs from one individual to another and results in variation in the size of the DNA segment.

As shown in the illustration, the sequence AGCT is repeated six times in the first person, five times in the second person and seven times in the third person. Because of this, the DNA segment of the third person will be larger in size followed by a DNA segment of first – person and then the second person. Thus it is clear that satellite DNA brings about variation within the population. Variation in the DNA banding pattern reveals differences among the individuals.

Question 4.
Write a detailed account of stem cells, types of stem cells and stem cell therapy?
Answer:
Our body is composed of over 200 specialised cell types, that can carry out specific functions, eg. Neurons or nerve cell that can transmit signals or heart cells which contract to pump blood or pancreatic cells to secrete insulin. These specialised cells are called differentiated cells. These specialised cells are called as differentiated cells. In contrast to differentiated cells, stem cells are the undifferentiated or unspecialised mass of cells. The stem cells are the cells of variable potency.
The two important properties of stem cells are:

  • its ability to divide and give rise to more stem cells by self-renewal,
  • its ability to give rise to specialised cells with specific functions by the process of differentiation.

Types of stem cells:

  1. Embryonic stem cells: These cells are extracted and cultured from the early embryos. These cells are derived from the inner cell mass of the blastocyst. These cells can be developed into any cell in the body.
  2. Adult stem cell or somatic stem cell: They are found in the neonatal (newborn) and adults. They have the ability to divide and give rise to specific cell types. The sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.
  3. Stem – cell therapy: Sometimes cells, tissues and organs in the body may be permanently damaged or lost due to genetic condition or disease or injury. In such situations, stem cells are used for the treatment of diseases, which is called stem cell therapy. In treating neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease neuronal stem cells can be used to replace the damaged or lost neurons.

Question 5.
(a) Explain genetically modified organisms |GMOs|.
(b) With the help of a tabular column tabulate the genetically modified plants and animals, with the objectives, gene inserted and achievement.
Answer:
(a) Genetic modification is the alteration or manipulation of genes in the organisms using rDNA techniques in order to produce the desired characteristics. The DNA fragment inserted is called transgene. Plants or animals expressing a modified endogenous gene or a foreign gene are also known as transgenic organisms.

The transgenic plants are much stable, with improved nutritional quality, resistant to diseases and tolerant to various environmental conditions. Similarly, transgenic animals are used to produce proteins of medicinal importance at low cost and improve livestock quality.

(b) Genetically modified plants and animals:
1. Genetically Modified Plants:

ObjectiveGene InsertedAchievement
Improved nutritional quality in RiceBeta carotene gene (In humans, Beta carotene is required for the synthesis of Vitamin A)Golden Rice (Genetically modified rice can produce beta carotene, that can prevent Vitamin A deficiency)
Increased crop productionBt gene from bacteria Bacillus thuringiensis. (Bt gene produces a protein that is toxic to insects)Insect resistant plants (These plants can produce the toxin protein that kills the insects which attack them)

2. Genetically Modified Animals:

ObjectiveGene insertedAchievement
The improved wool quality and productionGenes for synthesis of amino acid, cysteineTransgenic sheep (gene expressed)
Increased growth in fishesSalmon or Rainbow trout or Tilapia growth hormone geneTransgenic fish (gene expressed)

VII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Name the Indian scientist who is known for his leading role in India’s green revolution.
Answer:
Dr M. S. Swaminathan.

Question 2.
The application of biotechnology ‘A’ to treat a person born with a hereditary disease.
(a) What does ‘A’ mean?
(b) Mention its types.
Answer:
(a)

Question 5.
Rice normally grows well in alluvial soil, but _____ is a rice variety produced by mutation breeding that grows well in saline soil.
Answer:
Atomita – 2 rice

Question 6.
_____ technique made it possible to genetically engineer living organism.
Answer:
Recombinant DNA.

Question 7.
Restriction endonucleases cut the DNA molecule at specific positions known as ______.
Answer:
Molecular scissors.

Question 8.
Similar DNA fingerprinting is obtained for ______.
Answer:
Identical twins.

Question 9.
______ cells are undifferentiated mass of cells.
Answer:
Pleuripotent.

Question 10.
In gene cloning, the DNA of interest is integrated in a ______.
Answer:
Vector [plasmid].

III. State whether true or false. If false, write the correct statement.

Question 1.
Raphano brassica is a man – made tetraploid produced by colchicine treatment.
Answer:
True.

Question 2.
The process of producing an organism with more than two sets of chromosome is called mutation.
Answer:
False.
Correct statement: The process of producing an organism with more than two sets of chromosome is called polyploidy.

Question 3.
A group of plants produced from a single plant through vegetative or asexual reproduction are called a pureline.
Answer:
False.
Correct statement: A group of plants produced from a single plant through vegetative or asexual reproduction are called clones.

Question 4.
Iron fortified rice variety determines the protein quality of the cultivated plant.
Answer:
False.
Correct statement: Iron fortified rice variety determines the iron quality of the cultivated plant.

Question 5.
Golden rice is a hybrid.
Answer:
False.
Correct statement: Golden rice is a genetically modified plant.

Question 6.
Bt gene from bacteria can kill insects.
Answer:
True.

Question 7.
In vitro fertilisation means the fertilisation done inside the body.
Answer:
False.
Correct statement: In vitro fertilisation means the fertilisation done outside the body.

Question 8.
DNA fingerprinting technique was developed by Alec Jeffrey.
Answer:
True.

Question 9.
Molecular scissors refers to DNA ligases.
Answer:
False.
Correct statement: Molecular scissors refers to Restriction Enzymes.

IV. Match the following:

Question 1.

Column AColumn B
1. Sonalika(a) Phaseolus mungo
2. IR-8(b) Sugarcane
3. Saccharum(c) Semi-dwarf wheat
4. Mung No. 1(d) Groundnut
5. TMV-2(e) Semi-dwarf Rice
6. Insulin(f) Bacillus thuringienesis
7. Bt toxin(g) Beta carotene
8. Golden rice(h) the first hormone produced using rDNA technique

Answer:

  1. (c) Semi – dwarf wheat
  2. (e) Semi – dwarf Rice
  3. (b) Sugarcane
  4. (a) Phaseolus mungo
  5. (d) Groundnut
  6. (h) the first hormone produced using rDNA technique
  7. (f) Bacillus thuringienesis
  8. (g) Beta carotene.

V. Understand the assertion statement, justify the reason given and choose the correct choice:

(a) The assertion is correct and the reason is wrong.
(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason are correct.
(d) Both assertion and reason are wrong.

Question 1.
Assertion: Hybrid is superior to either of its parents.
Reason: Hybrid vigour is lost upon inbreeding.
Answer:
(a) The assertion is correct and the reason is wrong.

Question 2.
Assertion: Colchicine reduces the chromosome number.
Reason: It promotes the movement of sister chromatids to the opposite poles.
Answer:
(d) Both assertion and reason are wrong.

Question 3.
Assertion: rDNA is superior over hybridisation techniques.
Reason: Desired genes are inserted without introducing the undesirable genes in target organisms.
Answer:
(c) Both assertion and reason are correct.

VI. Answer in a Sentence

Question 1.
Give the name of the wheat variety having higher dietary fibre and protein.
Answer:
Atlas 66, a protein-rich variety, having higher dietary fibre and protein.

Question 2.
Semi-dwarf varieties were introduced in rice. This was made possible by the presence of dwarfing gene in rice. Name this dwarfing gene.
Answer:
Dee-geo-woo-gen a dwarf variety from China.

Question 3.
Define genetic engineering.
Answer:
Genetic engineering is the manipulation and transfer of genes from one organism to another organism to create a new DNA called recombinant DNA (rDNA). Genetic engineering is also called recombinant DNA technology.

Question 4.
Name the types of stem cells.
Answer:
Embryonic stem cells and somatic stem cells are the types of stem cells.

Question 5.
What are transgenic organisms?
Answer:
Plants or animals expressing a modified endogenous gene or a foreign gene are called transgenic organisms.

Question 6.
State the importance of biofertiliser.
Answer:
Biofertilizer adds nutrients through the natural process of nitrogen fixation, stimulate the plant growth through the synthesis of growth-promoting substance.

VII. Short Answer Questions

Question 1.
Discuss the method of breeding for disease resistance.
Answer:
Plant diseases are caused by pathogens like viruses, bacteria and fungi. This affects crop yield. To develop disease-resistant varieties of crops, that would increase the yield and reduce the use of fungicides and bactericides are important. Some disease-resistant varieties are as follows:

CropVarietyResistance to diseases
WheatHimgiriLeaf and stripe rust, hill bunt
CauliflowerPusa Shubhra, Pusa Snowball K-1Black rot
CowpeaPusa KomalBacterial blight

Question 2.
Name three improved characteristics of wheat that helped India to achieve high productivity.
Answer:
Sonalika, kalyan and sona are the three improved characteristic of wheat that helped India to achieve high productivity.

Question 3.
Name two maize hybrids rich in amino acid lysine.
Answer:
Protina, Shakti and Rathna are lysine – rich maize hybrids, which are developed in India.

Question 4.
Distinguish between
(a) Somatic gene therapy and germline gene therapy.
(b) Undifferentiated cells and differentiated cells.
Answer:
(a) Somatic gene therapy and germline gene therapy.

Somatic gene therapyGermline gene therapy
Somatic gene therapy is the replacement of the defective gene in somatic cells.Germline gene therapy is the replacement of the defective gene in the germ cell (egg and sperm).

(b) Undifferentiated cells and differentiated cells.

Undifferentiated cellsDifferentiated cells
Our body is composed of over 200 specialised cell types, that can carry out specific functions, eg. Neurons or nerve cells that can transmit signals. Pancreatic cells to secrete insulin. These specialised cells are called as differentiated cells.The cells which are variable potency, undifferentiated or unspecialised mass of cells are called stem cells. The stem cells are undifferentiated or unspecialised mass of cells.

Question 5.
State the applications of DNA fingerprinting technique.
Answer:
Applications of DNA Fingerprinting:
(i) DNA fingerprinting technique is widely used in forensic applications like crime investigation such as identifying the culprit. It is also used for paternity testing in case of disputes.
(ii) It also helps in the study of genetic diversity of population, evolution and speciation.

Question 6.
How are stem cells useful in the regenerative process?
Answer:
Sometimes cells, tissues and organs in the body may be permanently damaged or lost due to genetic condition or disease or injury. In such situations, stem cells are used for the treatment of diseases, which is called stem – cell therapy. In treating neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease neuronal stem cells can be used to replace the damaged or lost neurons.

Question 7.
Differentiate between outbreeding and inbreeding.
Answer:
Inbreeding:
When breeding or mating takes place between animals of the same breed, for about 4 – 6 generations, then it is called inbreeding. Superior males and superior females of the same breed are identified and mated in pairs. It helps in the accumulation of superior genes and the elimination of undesirable genes. Inbreeding depression is the continued inbreeding, which reduces fertility and productivity. Inbreeding exposes harmful recessive genes that are eliminated by selection.

Outbreeding:
The breeding of unrelated animals is outbreeding. The offsprings formed are called hybrids. The hybrids are stronger and vigorous than their parents. Cross between two different species with desirable features of economic value is mated. Mule is superior to the horse in strength, intelligence, ability to work and resistance to diseases, but they are sterile.

VIII. Long Answer Questions

Question 1.
What are the effects of hybrid vigour in animals.
Answer:

  1. Increased production of milk by cattle.
  2. Increased production of egg by poultry.
  3. High quality of meat is produced.
  4. Increased growth rate in domesticated animals.

Question 2.
Describe mutation breeding with an example.
Answer:
The mutation is defined as the sudden heritable change in the nucleotide sequence of DNA in an organism. The genetic variations brings out changes in an organism. The organism which undergoes mutation is called a mutant.
The factors which induce mutations are known as mutagens or mutagenic agents. The mutagens are of two types:
(a) Physical mutagens: Radiations like X – rays, a, P and Y – rays, UV rays and temperature, etc, which induce, maturations are called physical mutagens.

(b) Chemical mutagens: Chemical substances that induce mutations are called chemical mutagens, eg. Mustard gas and nitrous acid. The utilization of induced mutation in crop improvement is called mutation inbreeding.
Achievements of mutation breeding:

  • Sharbati Sonora wheat produced from Sonora – 64 by using gamma rays.
  • Atomica – 2 rice with saline tolerance and pest resistance.
  • Groundnuts with thick shells.

Question 3.
Biofortification may help in removing hidden hunger. How?
Answer:
Biofortification: Biofortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals. Some examples of crop varieties developed as a result of biofortification are given below:

  1. Protina, Shakti and Rathna are lysine rich maize hybrids (developed in India).
  2. Atlas 66, a protein rich wheat variety.
  3. Iron rich fortified rice variety’.
  4. Vitamin A enriched carrots, pumpkin and spinach.

Question 4.
With a neat labelled diagram explain the techniques involved in gene cloning.
Answer:
The carbon copy or more appropriately, a clone means to make a genetically exact copy of an organism. ‘Dolly’ is the cloned sheep.

In gene cloning, a gene or a piece of DNA fragment is inserted into a bacterial cell, where DNA will be multiplied (copied) as the cell divides.
The basic steps involved in gene cloning are:

  • Isolation of desired DNA fragment by using restriction enzymes.
  • Insertion of the DNA fragment into a suitable vector (plasmid) to make rDNA.
  • Transfer of rDNA into the bacterial host cell (Transformation).
  • Selection and multiplication of the recombinant host cell to get a clone.
  • Expression of the cloned gene in the host cell.

Using this strategy several enzymes, hormones and vaccines can be produced.

Question 5.
Discuss the importance of biotechnology in the field of medicine.
Answer:
Using genetic engineering techniques medicinally important valuable proteins or polypeptides that form the potential pharmaceutical products for the treatment of various diseases have been developed on a commercial scale.
Pharmaceutical products developed by rDNA technique:

  1. Insulin used in the treatment of diabetes.
  2. Human growth hormone used for treating children with growth deficiencies.
  3. Blood clotting factors are developed to treat haemophilia.
  4. Tissue plasminogen activator is used to dissolve blood clots and prevent heart attack.
  5. Development of vaccines against various diseases like Hepatitis B and rabies.

IX. Higher Order Thinking Skills (HOTS) Questions

Question 1.
A breeder wishes to incorporate desirable characters into the crop plants. Prepare a list of characters he will incorporate.
Answer:
The list of character he will incorporate are:

  1. High yielding and better quantity
  2. Disease resistance
  3. Insects pest resistance
  4. Improved nutritional quality
  5. Short duration

Question 2.
Organic farming is better than Green Revolution. Give reasons.
Answer:

  • Dwarfness is desired in cereals, so fewer nutrients are consumed by the crops.
  • Fertilizer is responsive.
  • Disease resistant varieties.
  • Insect and pest resistant crop varieties.
  • High levels of desirable nutrients like vitamins, proteins and minerals.

Question 3.
Polyploids are characterised by gigantism. Justify your answer.
Answer:
An organism having more than two set of chromosome is called polyploidy. It can be induced by physical agents such as heat or cold treatment, X-rays and chemical agents like colchicine. As organisms produced by polyploidy have more than two set of chromosomes they are gigantic.

Question 4.
‘P’ is a gene required for the synthesis of vitamin A. It is integrated with the genome of ‘Q’ to produce genetically modified plant ‘R’.
(i) What is P, Q and R?
(ii) State the importance of ‘R’ in India.
Answer:
(i)  The P, Q and R:

  • P – Beta – carotene gene.
  • Q – Prevent vitamin A deficiency.
  • R – Golden rice.

(ii) Importance of rice in India:

  • Rice is the most important staple food for millions of people in developing countries like India.
  • Beta – carotene is produced in the endosperm of the grain. It could control the chronic health problems caused by vitamin A deficiency, especially among the poor in developing countries like India.

Samacheer Kalvi 10th Science Breeding and Biotechnology

Additional Questions Solved

I. Fill in the blanks.

Question 1.
Plant ______ is the art of developing economically important plants.
Answer:
Breeding.

Question 2.
Plant diseases are caused by ______ like viruses, bacteria and fungi.
Answer:
Pathogen.

Question 3.
______ is the first man – made cereal hybrid.
Answer:
Triticale.

Question 4.
The superiority of the hybrid obtained by cross-breeding is called _____ or ______.
Answer:
Heterosis
or
Hybrid vigour.

Question 5.
The other name for genetic engineering is ______.
Answer:
Recombinant DNA technology.

Question 6.
The organism which undergoes mutation is called a ______ and the factors which induce mutations are ______.
Answer:
Mutant; mutagenic agents.

Question 7.
The replacement of the defective gene in a germ cell (egg or sperm) is called ______.
Answer:
Germline gene therapy.

Question 8.
Blood clotting factors are developed to treat ______.
Answer:
Haemophilia.

Question 9.
Stem cells, which are undifferentiated or unspecialised mass of cells can be used for the treatment is called ______.
Answer:
Stem cell therapy.

Question 10.
_______ is used in the treatment of diabetes.
Answer:
Insulin.

II. Match the following:

Question 1.

1. Cowpea(a) Joining the DNA fragments
2. UV rays(b) New breed of sheep
3. Lady’s finger(c) Bacterial blight
4. DNA ligase(d) Flat bean
5. Pusasem 3(e) Pusa Sawani
6. Hissardale(f) Induce mutation

Answer:
1. (c) Bacterial blight
2. (f) Induce mutation
3. (e) Pusa Sawani
4. (a) Joining the DNA fragments
5. (d) Flat bean
6. (b) New breed of sheep.

III. Write “True or False” statements. Correct the false statements:

Question 1.
Modem Agricultural practices are activities carried out to improve the plants.
Answer:
True.

Question 2.
When breeding takes place between animals of the same breed, it is called outbreeding.
Answer:
False.
Correct statement: When breeding takes place between animals of the same breed, it is called inbreeding.

Question 3.
The process of introducing high yielding varieties of plants from one place to another is called a selection.
Answer:
False.
Correct statement: The process of introducing high yielding varieties of plants from one place to another is called Exotic species.

Question 4.
The mutation is a sudden inheritable change in the nucleus sequence of DNA in an organism.
Answer:
False.
Correct statement: Mutation is a sudden heritable change in the nucleotide sequence of DNA in an organism.

Question 5.
A breed is a group of animals of common origin within a species, which has certain characters, that are not found in other members of the same species.
Answer:
True.

IV. Choose the correct answer.

Question 1.
The high yielding rice variety from Indonesia and China are ______.
(a) Peta and DGWG
(b) IR-8 and Gold rice
(c) Hexaploid Triticale and Triticum durum
(d) Sonalika and Kalyan Sona.
Answer:
(a) Peta and DGWG

Question 2.
First artificially synthesized hormone is:
(a) Secretin
(b) Insulin
(c) Glucagon
(d) Renin
Answer:
(b) Insulin

Question 3.
The presence of this substance in bacteria can undergo replication independently along with chromosomal DNA ______.
(a) heritable
(b) colchicine
(c) mutation
(d) plasmid.
Answer:
(d) plasmid.

Question 4.
Bacillus thuringiensis (Bt) stains have been used for designing novel.
(a) Bio-metallogical techniques
(b) Bio-insecticidal plants
(c) Bio-mineralization
(d) Bio-fertilizer
Answer:
(b) Bio-insecticidal plants

Question 5.
A group of plants produced from a single plant through vegetative or asexual reproduction is called ______.
(a) Transgenic
(b) Hexaploid
(c) clones
(d) mutation.
Answer:
(b) Hexaploid

V. Answer the following briefly:

Question 1.
What is the green revolution? Who is the “Father of Green Revolution”?
Answer:
Green Revolution is the process of increasing food production through high yielding crop varieties and modem agricultural techniques in underdeveloped and developing nations. Dr Norman. E. Borlaug, an American agronomist is the “Father of Green Revolution”.

Question 2.
Write the role of polyploidy in crop improvement.
Answer:
The role of polyploidy in crop improvement are production of:

  1. Seedless watermelons (3n) and bananas (3n).
  2. TV-29 (triploid variety of tea) with larger shoots and drought tolerance.
  3. Triticale (6n) is a hybrid of wheat and rye. To make this plant fertile polyploidy is induced. It has higher dietary fibre and protein.
  4. Raphanobrassica is an allotetraploid by colchicine treatment.

Question 3.
What is Bio – fortification? Give any two examples.
Answer:
Bio – fortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals.
Examples of crop varieties developed as a result of bio – fortification are:

  • Protina, Shakti and Rathna are lysine – rich maize hybrids.
  • Atlas 66, A protein – rich wheat variety.

Question 4.
Give two examples of cross-breeding in animals.
Answer:
Cross breed of fowls: White Leghorn X Plymouth Rock

Hybrid fowl – yield more eggs

Cross breed of cows : Developed by mating the bulls of exotic breeds and cows of indigenous breeds.
Brown Swiss X Sahiwal

Karan Swiss – yield 2-3 times more milk than indigenous cows.

Question 5.
What is hybridization? Explain the hybridization experiment.
Answer:
The process of crossing two or more types of plants for bringing their desired characters together into one progeny hybrid is called hybridization. Hybridization is creating a genetic variation to get improved varieties.

Hybridization Experiment:
Triticale is the first man-made cereal hybrid. It is obtained by crossing wheat (Triticum durum, 2n = 28) and rye (Secale cereal, 2n = 14). The F, a hybrid is sterile (2n = 21). Then the chromosome number is doubled using colchicine and it becomes hexaploid triticale (2n = 42). The cycle of crop raising and selection continues until the plants with the desired characters are finally obtained.

Question 6.
Name the methods of plant breeding for crop improvement.
Answer:
The methods of plant breeding to develop high yielding varieties, for crop improvement, are as follows:

  • Introduction of new varieties of plants
  • Selection
  • Polyploid breeding
  • Mutation breeding
  • Hybridization.

Question 7.
Explain briefly about gene therapy.
Answer:
The replacement of a defective gene by the direct transfer of functional genes into humans to treat genetic disease or disorder is referred to as gene therapy.
The recombinant DNA technology is used for gene therapy:

  • Somatic gene therapy is the replacement of the defective gene in somatic cells.
  • Gene line gene therapy is the replacement of the defective gene in the germ cell (egg or sperm).

Question 8.
What were the important discoveries that led to the stepping stones of recombinant DNA technology?
Answer:

  1. Presence of plasmid in bacteria that can undergo replication independently along with chromosomal DNA.
  2. Restriction enzymes cuts or break DNA at specific sites and are also called as molecular scissors.
  3. DNA ligases are the enzymes which help in ligating (joining) the broken DNA fragments.

Question 9.
What does modern agriculture include?
Answer:
Modem agricultural practices are activities carried out to improve the cultivation of plants. It includes:

  1. Preparation of soil
  2. Sowing
  3. Application of manures and fertilizers
  4. Proper irrigation
  5. Protection from weeds and pests
  6. Harvesting and threshing
  7. Storage

Question 10.
What is the aim of crop improvement?
Answer:
The aim of crop improvement is to develop improved crop varieties possessing higher yield, better quality, resistance to diseases and shorter duration.

Question 11.
(a) What are the two important properties of stem cells?
(b) Write a short note on two types of stem cells.
Answer:
(a) Properties of stem cells:
It’s the ability to divide and give rise to more stem cells by self-renewal.
It’s the ability to give rise to specialised cells with specific functions by the process of differentiation.

(b) Types of cells:

  • Embryonic stem cells: Embryonic stem cells are derived from the inner cell mass of the blastocyst, which can be extracted from the early embryos. These cells can be developed into any cell in the body.
  • Adult stem cell or somatic stem cell: These cells are found in the newborn and adults. They have the ability to divide and give rise to specific cell types. Sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.

Question 12.
What are bulk genomic DNA and satellite DNA?
Answer:
In human beings, 99 % of the DNA base sequences are the same and this is called a bulk genomic DNA. The remaining 1 % of the DNA sequence differs from one individual to another. This 1 % DNA sequence is present as a small stretch of repeated sequences, which is called satellite DNA.

VI. Answer the following in detail.

Question 1.
What are stem cells? Explain its types ooooo.
Answer:
Stem cells are undifferentiated or unspecialised mass of cells. The stem cells are the cells of variable potency. The two important properties of stem cells that differentiate them from other cells are:

  1. Its ability to divide and give rise to more stem cells by self-renewal.
  2. Its ability to give rise to specialised cells with specific functions by the process of differentiation.

Types of stem cells Embryonic stem cells can be extracted and cultured from the early embryos. These cells are derived from the inner cell mass of the blastocyst. These cells can be developed into air, cell in the body.

Adult stem cell or somatic stem cell are found in the neonatal (new bom) and adults. They have tne ability to divide and give rise to specific cell types. Sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.

Question 2.
Explain with examples the inbreeding and outbreeding of animal breeding.
Answer:
Animal breeding aims at the genotypes of domesticated animals to increase their yield and improve the desirable qualities to produce milk, egg and meat. When breeding takes place between animals of the same breed, it is called inbreeding.
The cross between different – breeds is called outbreeding.

1. Inbreeding:
Inbreeding refers to the mating of closely related animals within the same breed for about 4 – 6 generations. Superior males and superior females of the same breed are identified and mated in pairs. It helps in the accumulation of superior genes and elimination of genes, which are undesirable. Hissardale is a new breed of sheep developed in Punjab by crossing Bikaneri (Magra) ewes and Australian Marino rams.

2. Inbreeding depression:
Continued inbreeding reduces fertility and productivity. Inbreeding exposes harmful recessive genes that are eliminated by selection.

3. Outbreeding:
It is the breeding of unrelated animals. The offsprings formed are called hybrids. The hybrids are stronger and vigorous than their parents. Cross between two different species with desirable features of economic value are mated. Let’s see what cross produce a mule. Mule is superior to a horse in strength, intelligence, ability to work and resistance to diseases but they are sterile

Question 3.
Explain the DNA fingerprinting technology with an illustration.
Answer:
The DNA pattern of two individuals cannot be the same except for identical twins. Each persons DNA sequence is unique, due to the small difference in the base pairs. DNA fingerprinting is the easier and quicker method, to compare the genetic difference among the two individuals. This technique was developed by Alec Jeffrey.

Each individual’s unique DNA sequences provides distinct characteristics of an individual, which helps in identification. A variable number of tandem repeat sequences [VNTRs] serve as molecular markers for identification.

In human beings, 99 % of DNA base sequences are the same and this is called as bulk genomic DNA. The remaining 1 % DNA sequence differs from one individual to another. This 1 % DNA sequence is present as a small stretch of repeated sequences which is called as satellite DNA. The number of copies of the repeat sequence also called VNTRs differs from one individual to another and results in variation in the size of the DNA segment.

As shown in the illustration, the sequence AGCT is repeated six times in the first person, five times in the second person and seven times in the third person. Because of this, the DNA segment of the third person will be larger in size followed by a DNA segment of first – person and then the second person. Thus it is clear that satellite DNA brings about variation within the population. Variation in the DNA banding pattern reveals differences among the individuals.

Question 4.
Write a detailed account of stem cells, types of stem cells and stem cell therapy?
Answer:
Our body is composed of over 200 specialised cell types, that can carry out specific functions, eg. Neurons or nerve cell that can transmit signals or heart cells which contract to pump blood or pancreatic cells to secrete insulin. These specialised cells are called differentiated cells. These specialised cells are called as differentiated cells. In contrast to differentiated cells, stem cells are the undifferentiated or unspecialised mass of cells. The stem cells are the cells of variable potency.
The two important properties of stem cells are:

  • its ability to divide and give rise to more stem cells by self-renewal,
  • its ability to give rise to specialised cells with specific functions by the process of differentiation.

Types of stem cells:

  1. Embryonic stem cells: These cells are extracted and cultured from the early embryos. These cells are derived from the inner cell mass of the blastocyst. These cells can be developed into any cell in the body.
  2. Adult stem cell or somatic stem cell: They are found in the neonatal (newborn) and adults. They have the ability to divide and give rise to specific cell types. The sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.
  3. Stem – cell therapy: Sometimes cells, tissues and organs in the body may be permanently damaged or lost due to genetic condition or disease or injury. In such situations, stem cells are used for the treatment of diseases, which is called stem cell therapy. In treating neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease neuronal stem cells can be used to replace the damaged or lost neurons.

Question 5.
(a) Explain genetically modified organisms |GMOs|.
(b) With the help of a tabular column tabulate the genetically modified plants and animals, with the objectives, gene inserted and achievement.
Answer:
(a) Genetic modification is the alteration or manipulation of genes in the organisms using rDNA techniques in order to produce the desired characteristics. The DNA fragment inserted is called transgene. Plants or animals expressing a modified endogenous gene or a foreign gene are also known as transgenic organisms.

The transgenic plants are much stable, with improved nutritional quality, resistant to diseases and tolerant to various environmental conditions. Similarly, transgenic animals are used to produce proteins of medicinal importance at low cost and improve livestock quality.

(b) Genetically modified plants and animals:
1. Genetically Modified Plants:

ObjectiveGene InsertedAchievement
Improved nutritional quality in RiceBeta carotene gene (In humans, Beta carotene is required for the synthesis of Vitamin A)Golden Rice (Genetically modified rice can produce beta carotene, that can prevent Vitamin A deficiency)
Increased crop productionBt gene from bacteria Bacillus thuringiensis. (Bt gene produces a protein that is toxic to insects)Insect resistant plants (These plants can produce the toxin protein that kills the insects which attack them)

2. Genetically Modified Animals:

ObjectiveGene insertedAchievement
The improved wool quality and productionGenes for synthesis of amino acid, cysteineTransgenic sheep (gene expressed)
Increased growth in fishesSalmon or Rainbow trout or Tilapia growth hormone geneTransgenic fish (gene expressed)

VII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Name the Indian scientist who is known for his leading role in India’s green revolution.
Answer:
Dr M. S. Swaminathan.

Question 2.
The application of biotechnology ‘A’ to treat a person born with a hereditary disease.
(a) What does ‘A’ mean?
(b) Mention its types.
Answer:


(a) Gene therapy refers to the replacement of defective gene.
(b) The two type of gene therapy are Somatic and Germline.

Question 3.
Write the crossbreeds of the following:
(a) Crossbreed of fowls
(b) Crossbreed of cows
Answer:


(a) A crossbreed of fowls:

  • White Leghorn × Plymouth Rock

    Hybrid fowl – yield more eggs

(b) A crossbreed of cows:

  • Brown Swiss × Sahiwal

    Karan Swiss [yield 2 – 3 times more milk than indigenous cows]

Gene therapy refers to the replacement of defective gene.
(b) The two type of gene therapy are Somatic and Germline.

Question 3.
Write the crossbreeds of the following:
(a) Crossbreed of fowls
(b) Crossbreed of cows
Answer:
(a) A crossbreed of fowls:

  • White Leghorn × Plymouth Rock

    Hybrid fowl – yield more eggs

(b) A crossbreed of cows:

  • Brown Swiss × Sahiwal

    Karan Swiss [yield 2 – 3 times more milk than indigenous cows]

Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 19, Origin and Evolution of Life, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
Biogenetic law states that _____.
(a) Ontogeny and phylogeny go together.
(b) Ontogeny recapitulates phylogeny.
(c) Phylogeny recapitulates ontogeny.
(d) There is no relationship between phylogeny and ontogeny.
Answer:
(b) Ontogeny recapitulates phylogeny.

Question 2.
The ‘use and disuse theory’ was proposed by _____.
(a) Charles Darwin
(b) Ernst Haeckel
(c) Jean Baptiste Lamarck
(d) Gregor Mendel.
Answer:
(c) Jean Baptiste Lamarck

Question 3.
Paleontologists deal with _____.
(a) Embryological evidences
(b) Fossil evidences
(c) Vestigial organ evidences
(d) All the above.
Answer:
(b) Fossil evidences

Question 4.
The best way of direct dating fossils of recent origin is by _____.
(a) Radio – carbon method
(b) Uranium lead method
(c) Potassium – argon method
(d) Both (a) and (c).
Answer:
(a) Radio – carbon method

Question 5.
The term Ethnobotany was coined by _____.
(a) Khorana
(b) J.W. Harshberger
(c) Ronald Ross
(d) Hugo de Vries.
Answer:
(b) J.W. Harshberger

II. Fill in the blanks.

Question 1.
The characters developed by the animals during their life time, in response to the environmental changes are called _____.
Answer:
Acquired characters.

Question 2.
The degenerated and non-functional organs found in an organism are called _____.
Answer:
Vestigial organ.

Question 3.
The forelimbs of bat and human are examples of ______ organs.
Answer:
Homologous.

Question 4.
The theory of natural selection for evolution was proposed by _____.
Answer:
Charles Darwin.

III. State whether True or False. If false, write the correct statement.

Question 1.
‘The use and disuse theory of organs’ was postulated by Charles Darwin?
Answer:
False.
Correct statement: ‘The use and disuse theory of organs’ was postulated by Jean Baptiste Lamarck.

Question 2.
The homologous organs look similar and perform similar functions but they have different origin and developmental pattern?
Answer:
False.
Correct statement: The homologous organs look dissimilar and perform dissimilar functions, but they have the same origin and developmental pattern.

Question 3.
Birds have evolved from reptiles.
Answer:
True.

IV. Match the following:

Question 1.

Column AColumn B
1. Atavism(a) caudal vertebrae and vermiform appendix
2. Vestigial organs(b) a forelimb of a cat and a bat’s wing
3. Analogous organs(c) rudimentary tail and thick hair on the body
4. Homologous organs(d) a wing of a bat and a wing of an insect
5. Wood park(e) radiocarbon dating
6. W.F. Libby(f) Thiruvakkarai

Answer:

  1. (c) rudimentary tail and thick hair on the body
  2. (a) caudal vertebrae and vermiform appendix
  3. (d) a wing of a bat and a wing of an insect
  4. (b) a forelimb of a cat and a bat’s wing
  5. (f) Thiruvakkarai
  6. (e) radiocarbon dating.

V. Answer in a word or Sentence

Question 1.
A human hand, a front leg of a cat, a front flipper of a whale and a bat’s wing look dissimilar and adapted for different functions. What is the name given to these organs?
Answer:
Homologous organs.

Question 2.
Which organism is considered to be the fossil bird?
Answer:
Fossil bird Archaeopteryx.

Question 3.
What is the study of fossils called?
Answer:
Palaeontology.

VI. Short Answers Questions

Question 1.
The degenerated wing of a kiwi is an acquired character. Why is it an acquired character?
Answer:
Kiwi does not have the need to fly that is why they do not have wings. The characters developed by the animals during their life in response to environmental changes. The vestigial wings are so small (invisible) under the bristly, hair-like two-branched feathers. So the degenerated wing of a kiwi is an acquired character.

Question 2.
What is the study of fossils called?
Answer:
Palaeontology is called as the study of fossils.

Question 3.
Define Ethnobotany and write its importance.
Answer:
Ethnobotany is the study of a region’s plants and their practical uses through the traditional knowledge of the local culture of people.
Importance of Ethnobotany:

  • It provides traditional uses of the plant.
  • It gives information about certain unknown and known useful plants.
  • The ethnomedicinal data will serve as a useful source of information for the chemists, pharmacologists and practitioners of herbal medicine.
  • Tribal communities utilize ethnomedicinal plant parts like bark, stem, roots, leaves, flowers, flower bud, fruits, seeds, oils, resins, dyes and gum for the treatment of diseases like diarrhoea, fever, headache, diabetes, jaundice, snakebites and leprosy, etc.

Question 4.
How can you determine the age of the fossils?
Answer:
The age of fossils is determined by radioactive elements present in it. They may be carbon, uranium, lead or potassium.

VII. Long Answer Questions

Question 1.
Natural selection is a driving force for evolution-How?
Answer:
Darwin published his observations under the name “origin of species”. It elaborates on the theory of natural selection for evolutionary transformation.
The principles of Darwinism tells that natural selection is a driving force for evolution.

1. Overproduction: Living beings have the ability to reproduce and have the capacity to multiply in a geometrical manner.

2. Struggle for existence: Due to overproduction, a geometric ratio of increase in population occurs. The space to live and food available for the organisms remain the same. This creates a competition among the organisms, for food and space, leading to struggle.

  • The competition may be among the individuals of the same species (Intraspecific struggle).
  • Competition between the organisms of different species living together (Interspecific struggle).
  • Natural conditions like extreme heat or cold drought and floods can affect the existence of organisms (Environmental struggle).

3. Variations: Small variations are important for evolution. According to Darwin, favourable variations are useful to the organisms and unfavourable variations are harmful or useless to the organisms.

4. Survival of the fittest or Natural selection: During the struggle for existence, the organisms which can overcome the challenging situation, survive and adapt to the surrounding environment. Organisms, which are unable to face the challenges, are unfit to survive and disappear. The process of selection of organisms with favourable variation is called Natural selection.

5. Origin of species: According to Darwin, new species originates by the gradual accumulation of favourable variations for a number of generations.

Question 2.
How do you differentiate homologous organs from analogous organs?
Answer:

Homologous organsAnalogous organs
1. The homologous organs have been inherited from common ancestors, with similar developmental pattern in embryos.1. Analogous structures are shown in a batwing, a bird wing and an insect wing.
2. The forelimbs of a human hand, a front leg of a cat, the flipper of a whale and a bat’s, wing look dissimilar and adapted for different functions.2. The analogous organs look similar but perform similar functions.
3. Their mode of development and the basic structure of bone are similar.3. They have a different origin. Wings of insect are membranous extensions whereas wings of a bat is a bony structure. But performing the same function of flying.

Question 3.
How does fossilization occur in plants?
Answer:
A plant fossil is any preserved part of a plant that has died long back. Fossils may be a prehistoric impression that may be hundred to millions of years old. Majority of the plant fossils are disarticulated parts of plants, it is rare to find plants to be preserved as whole.

VIII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Arun was playing in the garden. Suddenly he saw a dragonfly sitting on a plant. He observed the wings of it. He thought it looked similar to a wing of a crow. Is he correct? Give a reason for your answer.
Answer:
No. He is not correct. Both crow and dragonfly have the same function of flying with wings. But it’s the origin (basic structure) is different. Dragonfly wing is the membranous extension. But the wing of the crow is the modification of forelimb.

Question 2.
Imprints of fossils tell us about evolution- How?
Answer:
Fossil records show that evolution has taken a gradual process from simple to complex organisms. The study of fossils helps us to understand the link of evolution. The origin of modem birds is supported by the evidence of palaeontology.

Question 3.
Octopus, cockroach and frog all have eyes. Can we group these animals together to establish a common evolutionary origin? Justify your answer.
Answer:
Convergent evolution is the process, by which the independently evolved features, may similar to each other, but can arise through different developmental pathways. So the octopus, cockroach and frog all have eyes. The independently evolved eye may similar in each other, but can arise through different developmental pathways.

Samacheer Kalvi 10th Science Origin and Evolution of Life Additional Questions Solved

I. Fill in the blanks.

Question 1.
The history of life has two aspects namely ______ and ______.
Answer:
Origin of life; The evolution of life.

Question 2.
The theory which postulates that life originates from pre – existing life is ______.
Answer:
Biogenesis.

Question 3.
_____ is the gradual change occurring in living organisms over a period of time.
Answer:
Evolution.

Question 4.
Sexual reproduction, which involves meiosis helps in the recombination of ______ during gametic fusion.
Answer:
Genes.

Question 5.
The major concept in astrobiology is the ______.
Answer:
Habitable zone.

Question 6.
The organisms, which live in extreme environmental conditions on Earth are called ______.
Answer:
Extremophiles.

Question 7.
Fossil records show that evolution has taken a gradual process from simple to _______ organisms.
Answer:
Complex.

II. Match the following:

Question 1.

1. Big Bang theory(a) study of regions and practical use of plants
2. Petrifaction(b) organisms buried and cause depression
3. Archaeopteryx(c) other names for astrobiology
4. Ethnobotany(d) preserve hard and soft parts
5. Mould(e) origin of the universe
6. Exobiology(f) fossil bird

Answer:

  1. (e) origin of the universe
  2. (d) preserve hard and soft parts
  3. (f) fossil bird
  4. (a) study of regions and practical use of plants
  5. (b) organisms buried and cause depression
  6. (c) other names for astrobiology.

Question 2.

1. Oparin and Haldane(a) use and disuse theory
2. Ernest Haeckel(b) Mutation theory
3. Leonardo da Vinci(c) Father of Indian palaeobotany
4. Jean Baptiste Lamarck(d) Life from the chemical reaction
5. Darwin(e) Father of palaeontology
6. De Vries(f) Radioactive carbon
7. Birbal Sahni(g) Ethnobotany
8. W.F. Libby(h) Origin of species
9. J.W. Harshberger(i) Biogenetic law

Answer:

  1. (d) Life from a chemical reaction
  2. (i) Biogenetic law
  3. (e) Father of palaeontology
  4. (a) use and disuse theory
  5. (h) Origin of species
  6. (b) Mutation theory
  7. (c) Father of Indian palaeobotany
  8. (f ) Radioactive carbon
  9. (g) Ethnobotany.

III. Choose the correct answer.

Question 1.
The theory of idea embodies that life on Earth is a divine creation ______.
(a) chemical reaction
(b) special creation
(c) spontaneous generation
(d) Biogenesis.
Answer:
(b) special creation

Question 2.
Palaeontology deals with the study of ______.
(a) analogous organs
(b) fossils
(c) gradual change
(d) homologous organ.
Answer:
(c) gradual change

Question 3.
The other name for continuous variation is ______.
(a) germinal variation
(b) somatic variation
(c) discontinuous variation
(d) fluctuating variation.
Answer:
(d) fluctuating variation.

Question 4.
It is a branch of palaeontology that deals with the recovery and identification of plant remain of geological past ______.
(a) palaeobotany
(b) Embryology
(c) mutation
(d) palaeontology.
Answer:
(a) palaeobotany

Question 5.
Book ‘Philosophic Zoologique’ published in the year 1809 was written by:
(a) Darwin
(b) Lamarck
(c) Wallace
(d) Mendel
Answer:
(b) Lamarck

IV. Answer the following shortly.

Question 1.
What is Abiogenesis?
Answer:
Abiogenesis or spontaneous generation theory states that life originated spontaneously from lifeless matter. It was believed that fishes originated from mud, frogs from moist soil and insects from decaying matter.

Question 2.
What is the cosmic origin?
Answer:
Cosmic origin of extraterrestrial theories states that life came from outer space. The unit of life called spores (panspermia) were transferred to different planets including Earth.

Question 3.
What is the chemical evolution of life?
Answer:
Chemical evolution of life theory states that life arose by a series of sequential chemical reactions. The first form of life could have come from pre – existing non – living inorganic molecules, which gave rise to the formation of diverse organic molecules, which are transformed into a colloid system to produce life.

Question 4.
Name the evidence of evolution What do they support?
Answer:

  • Evidence from morphology and Anatomy.
  • Evidence from embryology.
  • Evidence from palaeontology.

Evolution is best understood by observing the relationship between the existing organisms and the similarities of the extinct organisms. This evidence supports the concept that all organisms have evolved from common ancestors.

Question 5.
Explain the evidence of evolution from Embryology.
Answer:
The embryos from fish to mammals are similar in their early stages of development. The study of comparative embryology of different animals supports the concept of evolution. The differentiation of their special characters appears in the later stages of development. Ontogeny recapitulates phylogeny. The stages of development of the individual animal repeat the evolutionary history of the entire race of the animal.
Samacheer Kalvi 10th Science Solutions Chapter 19 Origin and Evolution of Life 1

Question 6.
Represent a flow chart showing the postulates of Lamarckism?
Answer:
The postulates of Lamarckism:

Question 7.
Explain the evidence of evolution from palaeontology.
Answer:
Palaeontology deals with the study of fossils. The study of fossils helps us to understand the line of evolution of many invertebrates and vertebrates. Fossil records show that evolution has taken a gradual process from simple to complex organisms.

The origin of modem birds is supported by the evidence from palaeontology. Archaeopteryx is the oldest known fossil bird. It is considered to be a connecting link between reptiles and birds. It had wings with feathers, like a bird. It had a long tail, clawed digits and conical teeth like a reptile.

Question 8.
What is evolution?
Answer:
Formation of new species due to changes in specific characters over several generations as a response to natural selection is called evolution. Evolution is the gradual change occurring in living organisms over a period of time.

Question 9.
Represent a flow chart showing the postulates of Darwinism?
Answer:
The postulates of Darwinism:

Question 10.
Explain the types of variation?
Answer:
Variations are the differences found among individuals of the same species and the offspring of the same parent. New species originate by the gradual accumulation of variations. Evolution would not be possible without variation.
Somatic variation and germinal variation are the two types of variations:

  1. Somatic variation: The variation which affects the body (somatic) cells of the organisms are called somatic variation, which is not heritable. They occur due to environmental factors.
  2. Geminal variation: The variations, which are produced in germ cells and inherited are called germinal variation. They are classified into two types.
    • Continuous variation: Small variations which occur among individuals of a population, and occur by gradual accumulation is called continuous variation. They are also called fluctuating variation, e.g. skin colour, height and weight and colour of the eye, etc.
    • Discontinuous variation: These changes are sudden, which occur in an organism, due to mutations. These large variations are not useful for evolution, e.g. short – legged Ancon sheep and six or more digits (fingers) in human, etc.

Question 11.
Explain the importance of fossils?
Answer:
Importance of fossils:

  1. They throw light on phylogeny and evolution of plants.
  2. Fossil plants give a historical approach to the plant kingdom.
  3. Fossils are useful in the classification of plants.
  4. Fossil plants can be used in the field of descriptive and comparative anatomy.

Question 12.
What are Extremophiles?
Answer:
The organisms which live in extreme environmental conditions on Earth are called extremophiles within our own solar system, there are many areas that are different from the Earth. We may find the presence of life similar to extremophile bacteria.

Question 13.
What is Astrobiology or Exobiology? What does it deal?
Answer:
Astrobiology or exobiology is the science which looks for the presence of extraterrestrial in the universe.
Astrobiology deals with the origin, evolution and distribution of life in the universe and to investigate the possibility of living in another world.

The major concept in astrobiology is the habitable zone. Astrobiology explains that any planets can support the existence of life if it fulfils two criteria:

  • It must have the right mass to retain an atmosphere.
  • It must have an orbit at the right distance from Sun, that it allows liquid water to exist. The distance needs to be neither too hot nor too cold and is often called the Goldilocks zone for life.

V. Answer the following in detail.

Question 1.
Explain in detail with diagrams, the evidence of evolution, through morphology and anatomy.
Answer:
The comparative study of morphology and anatomy of organisms have evolved from a common ancestor.

(ii) Analogous organs: The analogous organs look similar and perform similar functions but they have different origin and developmental pattern. The function of the wings of a bat, the wings of a bird and wings of an insect are similar, but their basic structures are different.

(iii) Vestigial organs: The degenerated and non¬functional organs of animals are called vestigial organs. The same organs are found to be well- developed and functional, in some of the related forms. Some of the vestigial organs in man are a vermiform appendix, nictitating membrane, caudal vertebra and coccyx, etc.

(iv) Atavism: The reappearance of ancestral characters in some individuals is called atavism, e.g. Presence of rudimentary tail in newborn babies, the presence of thick hair on the human body.

Question 2.
(a) Name the popular names of Lamarckism.
(b) Explain the principles of Lamarckism.
Answer:
(a) Lamarckism is the hypothesis that an organism can pass on characteristics, that it has acquired through use or disuse, during it’s lifetime to the offspring. Lamarck’s theory of evolution was published in ‘Philosophic Zoologique’ in the year 1809. Lamarckism is popularly known as ‘Theory of inheritance of Acquired Characters” or “Use and Disuse theory”

(b) (i) internal vital force: Due to the inherent ability of the living organisms or their component parts tend to increase in ‘ size continuously.

(ii) Environment and new needs: A change in the environment brings about changes in the need of the organisms. In response to the changing environment, the organisms develop certain adaptive characters. The adaptations may be in the form of development of new parts of the body.

(iii) Use and disuse theory: Lamarck’s use and disuse theory state that, if an organ is used constantly, the organ develops well and gets strengthened. When an organ is not used for a long time, it gradually degenerates. The ancestors of Giraffe were provided with a short neck and short forelimbs. Due to a shortage of grass, they are forced to feed on leaves from trees. The continuous stretching of their neck and forelimbs resulted in the development of long neck and long forelimbs, which is an example fcc constant use of an organ. The degenerated wing of Kiwi is an example for organ of disuse.

(iv) Theory of Inheritance of acquired characters: Animals respond to the changes when there is a change in the environment. The develop adaptive structures. The characters, developed during their lifetime, in response to the environmental changes are called acquired characters. The acquired characters are transmitted to the offspring by the process of inheritance.

VI. Higher-Order Thinking skills [HOTS] Questions

Question 1.

  1. What is the reason for the long neck of a giraffe.
  2. Name the theory based on the shown figure.

Answer:

  1. Due to a shortage of grass, they were forced to feed on leaves from trees. The continuous stretching of their neck and forelimb as resulted in the development of a long neck and long forelimbs.
  2. Theory of inheritance of acquired characters.

Question 2.
What are living fossils?
Answer:
Living fossils are living organisms that are similar in appearance to their fossilized distant ancestors and usually have no extinct close features, eg. Ginko Biloba.

Question 3.
What is Mars 2020 Astrobiology?
Answer:
NASA is developing the Mars 2020, Astrobiology to investigate an astrobiological relevant ancient environment on Mars, its surface geological processes and the possibility of past life on Mars and preservation of biosignatures within accessible geological materials.


Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 18, Heredity, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
According to Mendel, alleles have the following character ______.
(a) Pair of genes
(b) Responsible for character
(c) Production of gametes
(d) Recessive factors.
Answer:
(a) Pair of genes

Question 2.
9 : 3 : 3 : 1 ratio is due to:
(a) Segregation
(b) Crossing over
(c) Independent assortment
(d) Recessiveness
Answer:
(c) Independent assortment

Question 3.
The region of the chromosome where the spindle fibres get attached during cell division ______.
(a) Chromomere
(b) Centrosome
(c) Centromere
(d) Chromonema.
Answer:
(c) Centromere

Question 4.
The centromere is found at the centre of the ……… chromosome.
(a) Telocentric
(b) Metacentric
(c) Sub-metacentric
(d) Acrocentric
Answer:
(b) Metacentric

Question 5.
The ______ units form the backbone of the DNA.
(a) 5 carbon sugar
(b) Phosphate
(c) Nitrogenous bases
(d) Sugar phosphate.
Answer:
(c) Nitrogenous bases

Question 6.
Okasaki fragments are joined together by:
(a) Helicase
(b) DNA polymerase
(c) RNA primer
(d) DNA ligase
Answer:
(d) DNA ligase

Question 7.
The number of chromosomes found in human beings are ______.
(a) 22 pairs of autosomes and 1 pair of allosomes.
(b) 22 autosomes and 1 allosome.
(c) 46 autosomes.
(d) 46 pairs of autosomes and 1 pair of allosomes.
Answer:
(a) 22 pairs of autosomes and 1 pair of allosomes.

Question 8.
The loss of one or more chromosome in a ploidy is called:
(a) Tetraploidy
(b) Aneuploidy
(c) Euploidy
(d) polyploidy
Answer:
(b) Aneuploidy

II. Fill in the blanks.

Question 1.
The pairs of contrasting character (traits) of Mendel are called ______.
Answer:
Alleles or allelomorphs.

Question 2.
The physical expression of a gene is called ______.
Answer:
Phenotype.

Question 3.
The thin thread-like structures found in the nucleus of each cell are called ______.
Answer:
Chromosomes.

Question 4.
DNA consists of two _______ chains.
Answer:
Polynucleotide.

Question 5.
An inheritable change in the amount or the structure of a gene or a chromosome is called ______.
Answer:
Mutation.

III. Identify whether the statement is True or False. Correct the False Statement.

Question 1.
A typical Mendelian dihybrid ratio of F2generation is 3 : 1.
Answer:
False.
Correct statement: A typical Mendelian dihybrid ratio of F2 generation is 9 : 3 : 3 : 1.

Question 2.
A recessive factor is altered by the presence of a dominant factor.
Answer:
True.

Question 3.
Each gamete has only one allele of a gene.
Answer:
True.

Question 4.
hybrid is an offspring from a cross between genetically different parent.
Answer:
True.

Question 5.
Some of the chromosomes have an elongated knob-like appendage known as a telomere.
Answer:
False.
Correct statement: Some of the chromosomes have an elongated knob – like appendage known as the satellite.

Question 6.
New nucleotides are added and a new complementary strand of DNA is formed with the help of enzyme DNA polymerase.
Answer:
True.

Question 7.
Down’s syndrome is a genetic condition with 45 chromosomes.
Answer:
False.
Correct statement: Down’s syndrome is the genetic condition with 21 chromosomes.

IV. Match the following.

Question 1.

Column AColumn B
1. Autosomes(a) Trisomy 21
2. Diploid condition(b) 9 : 3 : 3 : 1
3. Allosome(c) 22 pair of chromosome
4. Down’s syndrome(d) 2n
5. Dihybrid ratio(e) 23rd pair of chromosome

Answer:
1. (c) 22 pair of chromosome
2. (d) 2n
3. (e) 23rd pair of chromosome
4. (a) Trisomy 21
5. (b) 9 : 3 : 3 : 1.

V. Answer in a Sentence.

Question 1.
What is a cross in which inheritance of two pairs of contrasting characters is studied?
Answer:
Dihybrid cross.

Question 2.
Name the conditions when both the alleles are identical.
Answer:
Homozygous

Question 3.
A garden pea plant produces axial white flowers. Another of the same species produced terminal violet flowers. Identify the dominant trait?
Answer:

  • Axial position – a dominant trait
  • White flowers – a recessive trait
  • Terminal position – a recessive trait
  • Violet flower – dominant trait.

Question 4.
What is the name given to the segments of DNA, which are responsible for the inheritance of a particular character?
Answer:
Genes

Question 5.
Name the bond which binds the nucleotides in a DNA.
Answer:
The hydrogen bonds bind the nucleotides in a DNA.

VI. Short Answer Questions.

Question 1.
Why did Mendel select pea plant for his experiments?
Answer:

  • The pea plant is self-pollinating and so it is very easy to raise pure breeding individuals.
  • It has a short life span, as it is an annual.
  • It is easy to cross-pollinate.
  • It has deeply defined contrasting characters.
  • The flowers are bisexual.

Question 2.
What do you understand by the term phenotype and genotype?
Answer:
Phenotype is the outward appearance or morphological character of an organism. The expression of gene or the genetic make up of an individual for a particular trait is called genotype.

Question 3.
What are allosomes?
Answer:
Out of 23 pairs of chromosomes, 22 pairs are autosomes and the 23rd pair is the allosome or sex chromosome.

Question 4.
What are Okazaki fragments?
Answer:
For the synthesis of new DNA, two things are required one is RNA primer and the enzyme primase. The DNA polymerase moves along the newly formed RNA primer nucleotides, which leads to the elongation of DNA. In the other strand, DNA is synthesis in small fragments called okazaki fragments. These fragments are linked by the enzyme called ligase.

Question 5.
Why is euploidy considered to be advantageous to both plants and animals?
Answer:
In euploidy condition, the individual bears more than the usual number of diploid chromosomes. The triploid plants and animals are sterile. The tetraploid plants, often result in increased fruit and flower size.

Question 6.
A pure tall plant (TT) is crossed with pure dwarf plant (tt), what would be the F1 and F2 generations? Explain.
Answer:
When a pure tall plant (TT) is crossed with pure dwarf plant (tt), In F1 generation all the plants will be tall. In F2 generation by selling the F1 monohybrid the tall and dwarf plant will be in the ratio of 3 : 1. In F2 generation phenotypic ratio will be 3 : 1. genotypic ratio will be 1 : 2 : 1

Question 7.
Explain the structure of a chromosome.
Answer:
The chromosomes are thin long and thread-like structures, consisting of two identical strands called sister chromatids. They are held together by a centromere. Each chromatid is made up of a spirally coiled thin structure called chromonema. The bead-like structures along the length are called chromomeres. The chromosomes are made up of DNA, RNA, chromosomal proteins (histones and non-histones) and certain metallic ions. These proteins give structural support to the chromosome.

Question 8.
Label the parts of the DNA in the diagram given below. Explain the structure briefly. Structure of DNA.
Answer:
DNA is the hereditary material as it contains the genetic information. DNA is a large molecule, consisting of millions of nucleotides. Each nucleotide consists of three compounds.

(a) A sugar molecule – Deoxy Ribose sugar

(b) A nitrogenous base [Purines and Pyrimidines]

  • Purines (Adenine and Guanine)
  • Pyrimidines (Cytosine and Thymine)

(c) A phosphate group Nucleoside and Nucleotide:
Nucleoside = Nitrogen base + sugar
Nucleotide = Nucleoside + Phosphate
The nucleotides are formed according to the purines and pyrimidines present in them.

VII. Long Answer Questions.

Question 1.
Explain with an example of the inheritance of the dihybrid cross. How is it different from a monohybrid cross?
Answer:
The dihybrid cross involves the inheritance of two pairs of contrast characteristics, round – yellow seeds and wrinkled – green seeds. When pea plants having round – yellow seeds cross – bred with pea plants having wrinkled – green seeds, in the first generation (F1), only round yellow seeds were produced.
No wrinkled – green seeds were obtained. Round yellow colour seeds were dominant and wrinkled-green seeds were recessive.

When round – yellow seeds were cross-bred by self-pollination, four types of seeds having different combinations of shape and colour were obtained in the F2generation. They were round- yellow, round-green, wrinkled-yellow and wrinkled – green seeds.

A dihybrid cross produced four types of F2offsprings in the ratio of 9 with two dominant traits, 3 with one dominant trait and one recessive trait, 3 with another dominant trait and another recessive trait and one with two recessive traits. The new combinations of traits with round green and wrinkled yellow had appeared in the dihybrid cross (F2 generation). The ratio of each phenotype of seeds in the F2generation is 9 : 3 : 3 : 1. This is known as the Dihybrid ratio.

Difference between a monohybrid cross and dihybrid cross:
Monohybrid cross:
Monohybrid cross is a genetic cross, that involves a single pair of genes, which is responsible for one trait.
Parents differ by a single trait.
Monohybrid ratio in F2 generation is 3 : 1.

Dihybrid cross:
Dihybrid cross is a genetic cross, that involves two pairs of genes, which are responsible for two traits,
The parents have two different independent traits.
The dihybrid ratio in the F2 generation is 9 : 3 : 3 : 1.

Question 2.
How is the structure of DNA organised? What is the biological significance of DNA?
Answer:
DNA is the hereditary material, as it contains the genetic information. It is a large molecule consisting of millions of nucleotides, so it is called a polynucleotide. Each nucleotide consists of three components.
(a) A sugar molecule – Deoxyribose sugar

(b) A nitrogenous base – There are two types of the nitrogenous base in DNA they are

  • Purines (Adenine and Guanine)
  • Pyrimidines (Cytosine and Thymine)

(c) A phosphate group – The polynucleotide chains from a double helix. Nitrogenous bases in the centre are linked to sugar – phosphate units, which form the backbone of the DNA. Pairing between the nitrogenous bases is very specific and is always between purine and pyrimidine, linked by hydrogen bonds.

Adenine (A) links Thymine (T) with two hydrogen bonds [A=T]. Cytosine (C) links Guanine (G) with three hydrogen bonds (C = G). The hydrogen bonds between the nitrogenous bases make the DNA molecule stable. The nucleotides in a helix are joined together by phosphodiester bonds.

The biological significance of DNA:

  • It is responsible for the transmission of heredity information from one generation to the next generation.
  • It contains the information required for the formation of proteins.
  • It controls the developmental process and life activities of an organism.

Question 3.
The sex of the newborn child is a matter of chance and neither of the parents may be considered responsible for it. What would be the possible fusion of gametes to determine the sex of the child?
Answer:
Out of 23 pairs of chromosomes, 22 pairs are autosomes and one pair (23rd pair) is the sex chromosome. The female gametes or the eggs formed are similar in their chromosome type [22 + XX], So human females are homogametic. The male gametes or sperms produced are of two types. They are produced in equal proportions. The sperm bearing [22 + X] chromosomes and the sperm bearing (22 + Y) chromosomes. So human males are called heterogametic.

It is a chance, as to which category of sperm fuses with the egg. If the egg [X] is fused by the X – bearing sperm an [XX] individual (female) is produced. If the egg [X] is fused by the Y – bearing sperm an [XY] individual (male) is produced. The sperm produced by the father determines the sex of the child. The mother is not responsible for determining the sex of the child.

VIII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Flowers of the garden pea are bisexual and self-pollinated. Therefore, it is difficult to perform hybridization experiment by crossing a particular pistil with the specific pollen grains. How Mendel made it possible in his monohybrid and dihybrid crosses?
Answer:
As the garden pea is self-pollinating plant the parent plant were emasculated to prevent self pollination.
The anthers were collected from male parent and dusted on the female parent and the stigma was bagged.

Question 2.
Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea – plants obtained in the F1 generation are then cross-bred to produce F2 generation of pea plants.

  1. What do the plants of the F1generation look like?
  2. What is the ratio of tall plants to dwarf plants in the F2 generation?
  3. Which type of plants was missing in F1, generation but reappeared in the F2 generation?

Answer:

  1. Tall
  2. 1 : 2 : 1
  3. Dwarf plants.

Question 3.
Kavitha gave birth to a female baby. Her family members say that she can give birth to only female babies because of her family history. Is the statement given by her family members true. Justify your answer.
Answer:
No, the statement is not true.
Sex determination is a chance of probability as to which category of sperm fuses with the eggs. If the egg(x) is fused by the x-bearing sperm, then
individual is female. If the egg (x) is fused by the y-bearing sperm then the individual is male. The sperm produced by the father only determines the sex of the child.

IX. Value-Based Questions

Question 1.
Under which conditions does the law of independent assortment hold good and why?
Answer:
Mendel gave this law based on his dihybrid cross experiment. Here the total number of individuals is F2 will be sixteen which occur in a ratio of 9 : 3 : 3 : 1 where two parental classes and two new combination will be produced.

Samacheer Kalvi 10th Science Heredity

Additional Questions Solved

I. Fill in the blanks.

Question 1.
The branch of biology that deals with the genes, genetic variation and heredity of living organisms is called ______.
Answer:
Genetics.

Question 2.
The chromatids are held together by ______.
Answer:
Centromere.

Question 3.
______ is the enzyme, which separates the double helix of DNA, above the replication fork.
Answer:
Topoisomerase.

Question 4.
_____ mutation is the changes occurring in the nucleotide sequence of a gene.
Answer:
Gene or point.

Question 5.
The end of the chromosome is called ______.
Answer:
Telomere.

Question 6.
The constriction of the chromosome at any point is called ______.
Answer:
Nuclear Zone.

Question 7.
The nucleotides in a helix are joined together by ______ bonds.
Answer:
Phosphodiester.

II. Match the following:

Question 1.

1. Homozygous(a) polynucleotide
2. Genes(b) human male
3. DNA(c) occurs in pairs and alike
4. Heterozygous(d) segments of DNA
5. Heterogametic(e) bind DNA to the origin of replication site
6. Autosome(f) occurs in pairs and unlike
7. Helicase(g) somatic characters

Answer:

  1. (c) occurs in pairs and alike
  2. (d) segments of DNA
  3. (a) polynucleotide
  4. (f) occurs in pairs and unlike
  5. (b) Human male
  6. (g) somatic characters
  7. (e) bind DNA to the origin of replication site.

III. Choose the correct answer.

Question 1.
The thin long thread-like structures consisting of two identical strands ______.
(a) Hybrid
(b) Chromosomes
(c) Genes
(d) DNA and RNA.
Answer:
(b) Chromosomes

Question 2.
A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because:
(a) Tallness is the dominant trait
(b) Shortness in the dominant trait
(c) Tallness in the recessive trait
(d) Height of pea plant is not governed by gene ‘T’ or ‘t’
Answer:
(a) Tallness is the dominant trait

Question 3.
The number, size and shape of chromosomes in the cell nucleus of an organism ______
(a) Karyotype
(b) Heterozygous
(c) Autosome
(d) Nucleotide
Answer:
(a) Karyotype

Question 4.
In human males all the chromosomes are paired perfectly except one. The unpaired chromosomes are:
(a) large chromosome
(b) small chromosome
(c) Y- chromosome
(d) X- chromosome
Answer:
(c) Y- chromosome

Question 5.
The addition or deletion in the number of chromosomes present in a cell is called _______
(a) Homogametic
(b) Polymerase
(c) Ploidy
(d) Nucleoside
Answer:
(c) Ploidy

IV. Write true or false for the statements. Correct the false statement.

Question 1.
The character which expresses itself is called the dominant condition and that which is masked is called recessive condition. Answer:
True

Question 2.
The chromosomes of body cells of an organism are haploid in condition and the single set of chromosomes in gametes are diploid in condition.
Answer:
False
Correct statement: The chromosomes of body cells of an organism are diploid in condition and the single set of chromosomes in gametes are haploid in condition.

Question 3.
The mother is responsible for determining the sex of the child. The sperm produced by the father does not determine the sex of the child.
Answer:
False
Correct statement: The mother is not responsible for determining the sex of the child. The sperm produced by the father determines the sex of the child.

Question 4.
The human female is called Homogametic. The human males are called heterogametic.
Answer:
True

Question 5.
Adenine always links with Guanine with three hydrogen bonds and cytosine always links with thymine with two hydrogen bonds.
Answer:
False
Correct statement: Adenine always links with thymine with two hydrogen bonds. Cytosine always links with Guanine with three hydrogen bonds.

V. Match the following persons with the correct statements.

Question 1.

1. Waldeyar(a) Role of chromosome in heredity
2. James Watson and Crick(b) Father of genetics
3. Hugo de Vries(c) Down’s syndrome
4. Langdon Down(d) Chromosomes
5. T.H Morgan(e) Mutation
6. Gregor Johan Mendel(f) Model of DNA

Answer:

  1. (d) chromosomes
  2. (f) Model of DNA
  3. (e) Mutation
  4. (c) Down’s syndrome
  5. (a) Role of chromosome in heredity
  6. (b) Father of genetics

VI. Answer the following in a word or with a sentence.

Question 1.
Who is the father of genetics?
Answer:
Gregor Johann Mendel.

Question 2.
Name the plant on which Mendel performed his experiment.
Answer:
Pisum sativum (Garden Pea).

Question 3.
What is locus?
Answer:
Each gene is present at a specific position on a chromosome called its locus.

Question 4.
Who proposed the double helical model of DNA?
Answer:
Watson and Crick

Question 5.
What does the dihybrid cross involve?
Answer:
The dihybrid cross involves the inheritance of two pairs of contrasting characteristics.

Question 6.
What are the components of chromosome?
Answer:
The components of chromosomes are DNA, RNA, chromosomal proteins like histones and non histones and certain metallic ions.

Question 7.
What are Nucleoside and Nucleotide?
Answer:
Nucleoside = Nitrogen base + sugar
Nucleotide = Nucleoside + phosphate

VII. Answer the following briefly.

Question 1.
Write the Law of purity of gametes.
Answer:
When a pair of contrasting alleles are brought together in a heterozygote, the two members of the allelic pair remain together without mixing and when gametes are formed, the two separate out, so that only one enters each gamete.

Question 2.
What are chromonema and chromomeres?
Answer:
Each chromatid is made up of a spirally coiled thin structure called chromonema. The chromonema has a number of bead – like structures along its length which are called chromomeres.

Question 3.
Explain the types of chromosome-based on the position of the centromere.
Answer:

Based on the position of the centromere, the chromosomes are classified as follows:

  • Telocentric: The centromere is at the proximal end. The chromosomes are rod – shaped.
  • Acrocentric: The centromere is found at the end with a short arm and a long arm. They are rod-shaped chromosomes.
  • Sub metacentric: The centromere is found near the centre of the – chromosome. Thus forming two unequal arms. They are J shaped or L shaped chromosomes.
  • Metacentric: The centromere occurs in the centre of the chromosome and forms two equal arms. They are V – shaped chromosomes.

Question 4.
Give reason for the appearance of new combination of characters in F2 progene.
Answer:
At the time of gamete formation in the F1Hybrid genes character asserted independently resulted in the appearance of new combination of character in the F2progene.

Question 5.
What is sickle cell anaemia?
Answer:
Sickle cell anaemia is caused by the mutation of a single gene. This alteration in gene brings a change in the structure of protein part of Haemoglobin molecule. The red blood cells, that carry the haemoglobin is sickle-shaped and oxygen-carrying capacity reduces, causing sickle cell anaemia.

Question 6.
Represent the phenotypic, genotypic ratio of both monohybrid cross and dihybrid cross in 72 generations of pea plants.
Answer:
Monohybrid cross:
Phenotypic ratio – 3 : 1
Genotypic ratio – 1 : 2 : 1

Dihybrid cross:
Phenotypic ratio – 9 : 3 : 3 : 1
Genotypic ratio – 1 : 2 : 2 : 1 : 4 : 1 : 2 : 2 : 1.

Question 7.
How do chromosomes take part in the formation of the male and female child?
Answer:
Fertilization of the egg (22 + X) with a sperm [22 + X] will produce a female child [44 + XX] The fertilization of the egg (22 + X) with a sperm [22 + Y] will give rise to a male child [44 + XY].

VIII. Answer the following in detail.

Question 1.
Explain the regions of chromosomes with a neat labelled diagram.
Answer:
The chromosomes are thin, long and thread-like structures, with two identical strands called chromatids. They are held together by a centromere. The chromatid is made up of spirally coiled, a thin structure called chromonema, which has a number of bead-like structures along its length called chromomeres.

A chromosome consists of the following regions:

Question 2.
Given an account of the Laws of Mendel.
Answer:
Mendel proposed three important laws which are now called as Mendel’s Laws of Heredity.
(i) Law of Dominance : “When two homozygous individuals with one or more sets of contrasting characters are crossed, the characters that appear in the F1 hybrid are dominant and those that do not appear in F1 are recessive characters”.

(ii) Law of Segregation or Law of purity of gametes : “When a pair of contrasting factors or genes or allelomorphs are brought together in a heterozygote or hybrid, the two members of the allelic pair remain together without mixing and when gametes are formed, the two separate out, so that only one enters each gamete.”

(iii) Law of independent assortment : “In case of inheritance of two or more pairs of characters simultaneously, the factors or genes of one pair assort out independently of the other pair.”

Question 3.
Explain the monohybrid cross, with a diagram and describe the interpretation of Mendel oh monohybrid cross.
Answer:
Crosses involving the inheritance of only one pair of contrasting characters are called monohybrid cross. It is a cross between two forms of a single trait like a cross between tall and dwarf plant. In a monohybrid cross, a pure breeding tall plant and a pure breeding dwarf plant, results, tall and monohybrids in the F1generation.

In the F2 generation, selfing of the F1monohybrids resulted in tall and dwarf plants in the ratio of 3 : 1. The external expression of a particular trait is known as the phenotype. So the phenotypic ratio is 3 : 1.
In the F2 generations, 3 different types were obtained.
Tall Homozygous – TT (pure) – 1
Tall Heterozygous – Tt – 2
Dwarf Homozygous – tt – 1
So the genotypic ratio 1 : 2 : 1.
A genotype is the genetic expression of an organism.

Mendel’s interpretation on monohybrid cross:
Factors are passed on from one generation to another, factors are referred to as genes. Tallness and dwarfism are determined by a pair of contrasting factors tall plant T, a dominant character and a plant is dwarf’s’, recessive character in pairs. Pure breeding tall plants (TT) and pure dwarf plants (tt) are called homozygous. If they are unlike, (Tt) they are referred to as heterozygous.

(i) Two factors make up a pair of contrasting characters are called alleles or allelomorphs. One member of each pair is contributed by one parent.

(ii) When two factors of a trait are brought together, by fertilization, only one expresses itself (tallness), masking the expression of the other (dwarfness). The character which expresses itself is called dominant and the character, which is masked is called recessive.

(iii) The factors for tallness [T] and dwarfness (t) are separate entities, and in a gamete either T or t is present. When F1hybrids are self crossed the two entities separate and then unite independently, forming tall and dwarf plants.

Question 4.
Explain Mendel’s laws of heredity with the results of a dihybrid cross.
Answer:
Mendel crossed pea plants having round yellow seeds (dominant) with pea plants having wrinkled green seeds. In the F1generation, round shape, yellow colour of the seeds were dominant over the wrinkled green colour seeds. When the hybrids of the F1 generation were cross-bred by self-pollination, the dihybrid cross, produced four types of F2 offsprings in the ratio of 9, with two dominant traits, 3 with one dominant trait and one recessive trait, 3 with another dominant trait and another recessive trait and 1 with two recessive traits.

Two new combinations of traits with round green and wrinkled yellow had appeared in the dihybrid cross. [F2generation]
Mendel’s law of heredity:
(i) Law of dominance: When two homozygous individuals with contrasting characters are crossed, the characters, that appear in the F1 hybrid are dominant and those do not appear in F1 are recessive characters.

(ii) Law of segregation or Law of purity of gametes: When a pair of contrasting factors or genes are brought together, in a heterozygote the contrasting pair remain together without, mixing and when gametes are formed, the two separate out so that only one enters each gamete.

(iii) Law of Independent Assortment: In case of inheritance of two or more pairs of characters simultaneously, the factors or genes of one pair assort out independently of the other pair.

Question 5.
Explain the Watson and Crick model of DNA.
Answer:
Watson and Crick model of DNA:
DNA molecules consist of two polynucleotide chains. These chains form a double helix. Structure, with two strands, which run anti-parallel to one another. Nitrogenous bases in the centre are linked to sugar – phosphate units, which form the backbone of the DNA. Pairing between the nitrogenous bases is very specific and is always between purine and pyrimidine linked by hydrogen bonds.

Adenine [A] links Thymine [T] with two hydrogen bonds (A = T)
Cytosine [C] links Guanine [G] with three hydrogen bonds (C = G). This is called complementary base pairing.
Hydrogen bonds between the nitrogenous bases make the DNA molecule stable.
Each turn of the double helix is 34 A° (3.4 nm). There are ten base pairs in a complete turn.
Nucleotides in a helix are joined together by phosphodiester bonds.

Question 6.
Explain in detail, the various steps of DNA replication.
Answer:
Replication of DNA:
Replication of DNA occurs within a cell. DNA molecule produces exact copies of its own structure during replication.
The two strands of a DNA molecule have complementary base pairs, the nucleotides of each strand, provide the information needed to produce its new strand. The two resulting daughter cells contain exactly the same genetic information as the parent cell.

DNA replication involves the following steps:
(a) Origin of replication: The points on the DNA, where replication begins, is the site of origin of replication. The two strands open and separate at this point, forming the replication fork.

(b) An unwinding of DNA molecule: The enzyme, helicase, bind to the origin of a replication site. Helicase separates the two strands of DNA. The enzyme called topoisomerase separates the double helix above the replication fork and removes the twists formed during the unwinding process.

(c) Formation of RNA primer: An RNA primer is a short segment of RNA nucleotides. The primer is synthesized by the DNA template, close to the origin of a replication site.

(d) Synthesis of the new complementary strand from the parent strand: After the formation of RNA primer, nucleotides are added with the help of an enzyme DNA polymerase, a new complementary strand of DNA is formed from each of the parent strands. The daughter strand is synthesized as a continuous strand, which is called the leading strand.

The short segments of DNA are synthesized, in the other strand and called lagging strand. The short segments of DNA are called Okazaki fragments. The enzyme DNA ligase joins the fragments. The replication fork of the two sides meets at a site called terminus, which is stimulated opposite to origin of a replication site.

IX. Higher Order Thinking Skills [HOTS] Questions

Question 1.
What do you understand about DNA, gene and chromosome in short?
Answer:
Deoxy ribonucleic acid [DNA] is the material located in the cells and nucleus, that makes up the chromosomes and genes. Its molecule is in the shape of a double helix.

A gene is a segment of DNA that is passed down from parents to children and confers a trait to the offspring. Genes are organised and packaged in units called chromosomes.

Chromosomes are thin, long thread-like structures contain two identical strands, called chromatids, held together by a centromere. Humans have 23 pairs of chromosomes.

Question 2.
What is the difference between a gene mutation and a chromosomal mutation?
Answer:

Gene mutationChromosomal mutation
1. A change in the nucleotide sequence, in a particular gene.1. A change in several genes in the chromosome.
2. Gene mutation is only a structural alteration.2. The chromosomal mutation is either numerical or structural changes in the entire DNA strand.

Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 17, Reproduction in Plants and Animals, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
The plant which propagates with the help of its leaves is ______.
(a) Onion
(b) Neem
(c) Ginger
(d) Bryophyllum.
Answer:
(d) Bryophyllum

Question 2.
Asexual reproduction takes place through budding in:
(a) Amoeba
(b) Yeast
(c) Plasmodium
(d) Bacteria
Answer:
(b) Yeast

Question 3.
Syngamy results in the formation of ______.
(a) Zoospores
(b) Conidia
(c) Zygote
(d) Chlamydospores.
Answer:
(c) Zygote

Question 4.
The essential parts of a flower are:
(a) Calyx and Corolla
(b) Calyx and Androecium
(c) Corolla and Gynoecium
(d) Androecium and Gynoecium
Answer:
(d) Androecium and Gynoecium

Question 5.
Anemophilous flowers have ______.
(a) Sessile stigma
(b) Small smooth stigma
(c) Coloured flower
(d) Large feathery stigma.
Answer:
(d) Large feathery stigma.

Question 6.
Male gametes in angiosperms are formed by the division of:
(a) Generative cell
(b) Vegetative cell
(c) Microspore mother cell
(d) Microspore
Answer:
(a) Generative cell

Question 7.
What is true of gametes?
(a) They are diploid
(b) They give rise to gonads
(c) They produce hormones
(d) They are formed from gonads.
Answer:
(d) They are formed from gonads.

Question 8.
A single highly coiled tube where sperms are stored, get concentrated and mature is known as:
(a) Epididymis
(b) Vasa efferentia
(c) Vas deferens
(d) Seminiferous tubules
Answer:
(a) Epididymis

Question 9.
The large elongated cells that provide nutrition to developing sperms are ______.
(a) Primary germ cells
(b) Sertoli cells
(c) Leydig cells
(d) Spermatogonia.
Answer:
(b) Sertoli cells

Question 10.
Estrogen is secreted by:
(a) Anterior pituitary
(b) Primary follicle
(c) Graffian follicle
(d) Corpus luteum
Answer:
(c) Graffian follicle

Question 11.
Which one of the following is an IUCD?
(a) Copper – T
(b) Oral pills
(c) Diaphragm
(d) Tubectomy.
Answer:
(a) Copper – T

II. Fill in the Blanks.

Question 1.
The embryo sac in a typical dicot at the time of fertilization is ______.
Answer:
Female Gametophyte.

Question 2.
After fertilization the ovary develops into ______.
Answer:
Fruit.

Question 3.
Planaria reproduces asexually by ______.
Answer:
Regeneration.

Question 4.
Fertilization is ______ in humans.
Answer:
Internal.

Question 5.
The implantation of the embryo occurs at about ______ day of fertilization.
Answer:
6 to 7.

Question 6.
_______ is the first secretion from the mammary gland after childbirth.
Answer:
Colostrum.

Question 7.
Prolactin is a hormone produced by ______.
Answer:
Anterior Pituitary.

III. Match the following.

Question 1.

Column IColumn II
1. Fission(a) Spirogyra
2. Budding(b) Amoeba
3. Fragmentation(c) Yeast

Answer:
1. (b) Amoeba
2. (c) Yeast
3. (a) Spirogyra.

Question 2.
Match the following terms with their respective meanings.

1. Parturition(a) The duration between pregnancy and birth
2. Gestation(b) Attachment of zygote to the endometrium
3. Ovulation(c) Delivery of baby from a uterus
4. Implantation(d) Release of an egg from Graafian follicle

Answer:
1. (c) Delivery of baby from a uterus
2. (a) Duration between pregnancy and birth
3. (d) Release of the egg from Graafian follicle
4. (b) Attachment of zygote to the endometrium.

IV. State whether the following statements are True or False. Correct the false statement.

Question 1.
The stalk of the ovule is called pedicle.
Answer:
False.
Correct Statement: Stalk of the ovule is called funiculus.

Question 2.
Seeds are the product of asexual reproduction.
Answer:
False.
Correct Statement: Seeds are the product of Sexual reproduction.

Question 3.
Yeast reproduces asexually by means of multiple fission.
Answer:
False.
Correct Statement: Yeast reproduces asexually by means of budding.

Question 4.
The part of the pistil which serves as a receptive structure for the pollen is called as style.
Answer:
False.
Correct Statement: The part of the pistil which serves as a receptive structure for the pollen is called as stigma.

Question 5.
Insect pollinated flowers are characterized by dry and smooth pollen.
Answer:
False.
Correct Statement: Insect pollinated flowers are characterized by larger and spiny pollen.

Question 6.
Sex organs produce gametes, which are diploid.
Answer:
False.
Correct Statement: Sex organs produce gametes, which are haploid.

Question 7.
LH is secreted by the posterior pituitary.
Answer:
False.
Correct Statement: LH is secreted by the anterior pituitary.

Question 8.
Menstrual cycle ceases during pregnancy.
Answer:
True.

Question 9.
Surgical methods of contraception prevent gamete formation.
Answer:
True.

Question 10.
The increased level of estrogen and progesterone is responsible for menstruation.
Answer:
False.
Correct Statement: The decreased level of estrogen and progesterone is responsible for menstruation.

V. Answer in a word or sentence.

Question 1.
If one pollen grain produces two male gametes, how many pollen grains are needed to fertilize 10 ovules?
Answer:
One sperm fuses with the egg and forms a diploid zygote. So 10 pollen grains are needed to fertilize 10 ovules.

Question 2.
In which part of the flower germination of pollen grains takes place?
Answer:
Germination of pollen grains takes place in the stigma of the female flower.

Question 3.
Name two organisms which reproduce through budding.
Answer:
Yeast, Hydra.

Question 4.
Mention the function of endosperm.
Answer:
Endosperm provides food to the developing embryo.

Question 5.
Name the hormone responsible for the vigorous contractions of the uterine muscles.
Answer;
Oxytocin, from the posterior pituitary, is responsible for the vigorous contractions of the uterine muscles.

Question 6.
What is the enzyme present in acrosome of sperm?
Answer:
Acrosome contain hyaluronidase an enzyme that help the sperm to enter the ovum during fertilization.

Question 7.
When is World Menstrual Hygiene Day observed?
Answer:
Every year May 28 is observed as World Menstrual Hygiene Day.

Question 8.
What is the need for contraception?
Answer:
Contraception is one of the best birth control measures to check population growth.

Question 9.
Name the part of the human female reproductive system where the following occurs.

  1. Fertilization
  2. Implantation

Answer:

  1. Oviduct of the female genital tract.
  2. Uterus

VI. Short Answer Questions.

Question 1.
What will happen if you cut Planaria into small fragments?
Answer:
Breaking of fragments of Planaria results into many fragments. Each fragment having one cell will give rise to a new Planaria, by cell division.

Question 2.
Why is vegetative propagation practiced for growing some type of plants?
Answer:
No gametic fusion is required in vegetative reproduction. In this type, new plantlets are formed from vegetative cells, buds or organ of plant. The vegetative part of plant get detached from the parent body and grows into an Independent daughter plant.

Question 3.
How does binary fission differ from multiple fission?
Answer:

Binary fissionMultiple fission
1. The nucleus divides into two parts.1. The nucleus divides into many parts.
2. It gives rise to new individuals.2. It gives rise to many individuals
3. Cytoplasm divides after each nuclear division.3. Cytoplasm does not divide after every nuclear division.
4. eg. Amoeba.4. eg. Plasmodium.

Question 4.
Define Triple fusion.
Answer:
The fusion of one male gamete (n) fuses with the secondary nucleus (2n) to produce primary endosperm nucleus (3n) is called Triple fusion.

Question 5.
Write the characteristics of insect-pollinated flowers.
Answer:
Pollination with the help of insects like flies and honey bees are called Entomophily. To attract those insects, these flowers are brightly coloured, have smell and nectar.

Question 6.
Name the secondary sex organs in male.
Answer:
Secondary sex organs in male are seminiferous tubules, epididymis, sperm duct, seminal vesicles, prostrate gland, cowper’s gland and penis.

Question 7.
What is colostrum? How is milk production hormonally regulated?
Answer:
The first fluid which is released from the mammary gland after childbirth is called colostrum. Milk production from alveoli of the mammary gland is stimulated by prolactin secreted from the anterior pituitary. The ejection of milk is stimulated by the posterior pituitary hormone oxytocin.

Question 8.
How can menstrual hygiene be maintained during menstrual days?
Answer:
Menstrual hygiene to be maintained during menstrual days are:

  1. Sanitary pads should be changed regularly to avoid infections due to microbes from vagina and sweat from genitals.
  2. Use of warm water to clean genitals helps to get rid of menstrual cramps.
  3. Wearing loose clothing rather than tight-fitting clothes will ensure the airflow around the genitals and prevent sweating.

Question 9.
How does developing embryo gets its nourishment inside the mother’s body?
Answer:
The placenta allows the exchange of food materials, diffusion of oxygen, excretion of nitrogenous wastes and elimination of carbon-di-oxide. A cord, containing blood vessels that connect the placenta with the foetus is called the umbilical cord.

Question 10.
Identify the parts A, B, C and D.
Samacheer Kalvi 10th Science Solutions Chapter 17 Reproduction in Plants and Animals 1
Answer:
The parts A, B, C and D are:
Samacheer Kalvi 10th Science Solutions Chapter 17 Reproduction in Plants and Animals 2

Question 11.
Write the events involved in the sexual reproduction of a flowering plant.
(a) Discuss the first event and write the types.
(b) Mention the advantages and the disadvantages of that event.
Answer:
(a) The first event is pollination. Pollination is the process of transfer of pollen grains from anther to stigma of a flower. The two types of pollination are self-pollination and cross pollination.

(b) Advantages of self-pollination:

  1. Self-pollination is possible in certain bisexual flowers.
  2. Flowers do not depend on agents for pollination.
  3. There is no wastage of pollen grains.

Disadvantages of self-pollination:

  1. The seeds are less in numbers.
  2. The endosperm is minute. Therefore, the seeds produce weak plants.
  3. New varieties of plants cannot be produced.

Advantages of cross pollination:

  1. The seeds produced as a result of cross pollination, develop and germinate properly and grow into better plants, i.e., cross pollination leads to the production of new varieties.
  2. More viable seeds are produced.

Disadvantages of cross-pollination:

  1. Pollination may fail due to distance barrier.
  2. More wastage of pollen grains.
  3. It may introduce some unwanted characters.
  4. Flowers depend on the external agencies for pollination.

Question 12.
Why are the human testes located outside the abdominal cavity? Name the pouch in which they are present?
Answer:
The testicles, produce sperm and testosterone. The testicles are located outside the body because the sperms develop best at a temperature, several degrees lower than normal body temperature. The pouch, is scrotum, a sac – like structure, in which the testes are present.

Question 13.
Luteal phase of the menstrual cycle is also called the secretory phase. Give reason.
Answer:
In leutal phase LH and FSH decreases, corpus luteum produces progesterone and its level increases followed by a decline progesterone also stimulates the glands in the uterus to secrete substances that maintain the endometrium and keep it from breaking down. For this reason, this phase of menstrual cycle is called secretory phase.

Question 14.
Why are family planning methods not adopted by all the people of our country?
Answer:

  • Illiteracy
  • Emphasis is in rural areas and not in villages.
  • Door to door campaign to encourage families could not be done because of overpopulation.
  • Poor economic status and poverty of most of the people in India.
  • Age-Old cultural norms continue to cause, poor family planning practices, all across the country.

VII. Long Answer Questions.

Question 1.
With a neat labelled diagram describe the parts of a typical angiosperms ovule.
Answer:
The main part of the ovule is the nucellus which is enclosed by two integuments, leaving an opening called micropyle. The ovule is attached to the ovary wall by a stalk, called funiculus. The basal part is Chalaza.


Samacheer Kalvi 10th Science Solutions Chapter 17 Reproduction in Plants and Animals 3

The embryo sac contains seven cells and the eighth nuclei located within the nucellus. Three cells at the micropylar end form the egg apparatus and the three cells at the chalazalnte9uments end are the antipodal cells. The remaining two nuclei are called polar nuclei found in the centre. In the egg apparatus, one is the egg cell (female gamete) and the remaining two cells are the synergids.

Question 2.
What are the phases of the menstrual cycle? Indicate the changes in the ovary and uterus.
Answer:
The four phases of the menstrual cycle are:

  • Menstrual or Destructive phase
  • Follicular or Proliferative phase
  • Ovulatory phase
  • Luteal or secretory phase.

Events of the menstrual cycle and changes in ovary and changes in the uterus.

PhaseDaysChanges in OvaryChanges in UterusHormonal changes
Menstrual phase4 – 5 daysDevelopment of primary follicles.Breakdown of uterine endometrial lining leads to bleeding.The decrease in progesterone and oestrogen.
Follicular phase6th – 13th
day
Primary follicles grow to become a fully mature Graafian follicle.Endometrium regenerates through proliferation.FSH and Oestrogen increase.
Ovulatory phase14th dayThe Graafian follicle ruptures, and releases the ovum (egg).Increase in endometrial thickness.LH peak.
Luteal phase15th – 28th dayEmptied Graafian follicle develops into corpus luteum.The endometrium is prepared for implantation if fertilization of the egg takes place if fertilization does not occur corpus luteum degenerates, uterine wall ruptures, bleeding starts and unfertilized egg is expelled.LH and FSH decrease, Corpus luteum produces progesterone and its level increases followed by a decline, if menstrual bleeding occurs.

VIII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
In angiosperms the pollen germinates to produce pollen tube that carries two gametes. What is the purpose of carrying two gametes when single gamete can fertilize the egg?
Answer:
In angiosperms, one sperm cell fuses with the egg cell to form the zygote, while the other fuses with the two polar nuclei that form the endosperm which nourishes the developing embryo.

Question 2.
Why the menstrual cycle does not take place before puberty and during pregnancy?
Answer:
The reproducing period of a women’s life starts and becomes functional and an increase in sex hormone production starts only in puberty. So the menstrual cycle does not take place before puberty. The release of a mature egg, maintains the lining of the uterus, during pregnancy. During pregnancy, the placenta produces progesterone. This maintains the lining of the uterus during pregnancy and it means that menstruation does not happen.

Question 3.
Read the following passage and answer the questions that follow.
Rahini and her parents were watching a television programme. An advertisement flashed on the screen which was promoting use of sanitary napkins. Rahini’s parents suddenly changed the channel, but she objected to her parents and explained the need and importance of Such advertisement.

(a) What is first menstruation called? When does it occur?
Answer:
The first menstruation is called Menarche. In human females, the menstrual cycle starts at the age of 11 – 13 years which marks the onset of puberty.

(b) List out the napkin hygiene measures taken during menstruation?
Answer:

  1. The sanitary pad and tampons should be wrapped properly and discarded because they can spread infections.
  2. Sanitary pad or tampon should not be flushed down the toilet.
  3. Napkin incinerators are to be used properly for disposal of used napkins.

(c) Do you think that Rahini’s objection towards her parents was correct? If so, Why?
Answer:
Yes. Awareness to be created in maintaining menstrual hygeine and importance of menstrual hygeine for good health.

Samacheer Kalvi 10th Science Reproduction in Plants and Animals

Additional Questions Solved

I. Fill in the blanks.

Question 1.
The reproduction process is to preserve individual species and is called ______.
Answer:
Self – perpetuation.

Question 2.
The _______ grains are produced in the anther within the pollen sac.
Answer:
Pollen.

Question 3.
The _____ contains the future plant or embryo, which develops into a seedling.
Answer:
Seed.

Question 4.
Each testis is covered with a layer of fibrous tissue called ______.
Answer:
Tunica albuginea.

Question 5.
The first fluid which is released from the mammary gland after childbirth is called ______.
Answer:
Colostrum.

Question 6.
The organs of the reproductive system are divided into ______ and ____ (accessory) sex organs.
Answer:
Primary, secondary.

Question 7.
The plasma membrane of an ovum is surrounded by inner thin _____ and an outer thick ______.
Answer:
Zona pellucida, Corona Radiata.

Question 8.
______ is the practice of healthy living and personal cleanliness.
Answer:
Hygiene.

Question 9.
Testosterone initiates the process of ______.
Answer:
Spermatogenesis.

Question 10.
The cortex of ovary is composed of a connective tissue called ______.
Answer:
Stroma.

Question 11.
In plants, the fusion of one sperm with the egg is called ______.
Answer:
Syngamy.

Question 12.
The _______ provides energy for the movement of the tail in sperm, causing sperm motility, which is essential for fertilization.
Answer:
Mitochondria.

Question 13.
Self – pollination is also known as ______.
Answer:
Autogamy

Question 14.
During spore formation, a structure called sporangium develops from the ______.
Answer:
Fungal hyphae.

II. Choose the correct pair from the following.

Question 1.
(a) Chalaza and pollination
(b) Calyx and spores
(c) Anemophily and hydrophily
(d) Stamens and Planaria.
Answer:
(c) Anemophily and hydrophily

Question 2.
(a) Oogenesis and spermatogenesis
(b) Fragmentation and Fertilization
(c) Primary follicle and fission
(d) Micropyle and Regeneration.
Answer:
(a) Oogenesis and spermatogenesis

Question 3.
(a) Scrotum and sporangium
(b) Pollination and population
(c) Spermatogenesis and seminiferous tubules
(d) Diaphragm and Blastocyst.
Answer:
(c) Spermatogenesis and seminiferous tubules

Question 4.
(a) Autogamy and Budding
(b) Funiculus and chalaza
(c) Bulbils and spirogyra
(d) Polar nuclei and pollination.
Answer:
(b) Funiculus and chalaza

Question 5.
(a) Tuberous root and granulosa cells
(b) Corolla and Graafian follicle
(c) Synergids and Regeneration
(d) The vegetative and generative cell.
Answer:
(d) The vegetative and generative cell.

III. Match the following.

Question 1.

1. Offsprings(a) Pollination by insects
2. Anemophily(b) Pollination by animals
3. Spermatogenesis(c) Blood vessels
4. Umbilical cord(d) Expulsion of the young one
5. Entomophily(e) Seminiferous tubules
6. Parturition(f) Sexual reproduction
7. Zoophily(g) Pollination by wind

Answer:

  1. (f) Sexual reproduction
  2. (g) Pollination by wind
  3. (e) Seminiferous tubules
  4. (c) Blood vessels
  5. (a) Pollination by insects
  6. (d) Expulsion of the young one
  7. (b) Pollination by animals.

IV. Choose the correct answer.

Question 1.
The male and the female gametes contain this material on the chromosomes, which transmit the character traits to the next generation.
(a) genes
(b) chromoplast
(c) septum
(d) spores
Answer:
(a) genes

Question 2.
Raphe and hilium in seed represent:
(a) Nucellus
(b) Funiculus
(c) Integument
(d) Micropyle
Answer:
(b) Funiculus

Question 3.
The corona radiata is formed of ______.
(a) Vitelline membrane
(b) Oxytocin
(c) Zygote
(d) Follicle.
Answer:
(d) Follicle.

Question 4.
Pollination is followed by:
(a) Seed formation
(b) Fragmentation
(c) Fertilization
(d) Budding
Answer:
(c) Fertilization

Question 5.
The membrane forming the surface layer of the ovum is called ______.
(a) Entomophily
(b) Exine
(c) Vitelline membrane
(d) Intine.
Answer:
(c) Vitelline membrane

V. Write True or False for the following statements. Write the correct statement for the incorrect statement.

Question 1.
Sexual reproduction involves the fusion of two diploid gametes to form a haploid individual (Zygote).
Answer:
False.
Correct Statement: Sexual reproduction involves the fusion of two haploid gametes, to form a diploid individual (Zygote).

Question 2.
Accessory sex organ in man includes the Gonads. (Testes in males and Ovaries in female).
Answer:
False.
Correct Statement: Primary sex organ in man include the Gonads. (Testes in males and Ovaries in female).

Question 3.
The connective tissue of Cortex called stroma is lined by the germinal epithelium cells called Granulosa cells.
Answer:
True.

Question 4.
The mature ovum or egg in the female is elliptical in shape and has full of yolk.
Answer:
False.
Correct Statement: The mature ovum or egg is spherical in shape and is always free of yolk.

Question 5.
The menstrual cycle ceases around 48-50 years of age and this stage is termed as menopause.
Answer:
True.

VI. Answer the following briefly.

Question 1.
What is the role of acrosome in human sperm?
Answer:
The sperm head has a like structure called acrosome. It contain hyaluronidase an enzyme that helps the sperm to enter the ovum during fertilization.

Question 2.
What are the significance of fertilization and the post-fertilization changes?
Answer:
Significance of fertilization:

  • It stimulates the ovary to develop into a fruit.
  • It helps in the development of new characters from two different individuals.

Post – fertilization changes:

  • The ovule develops into a seed.
  • The integuments of the ovule develop into the seed coat.
  • The ovary enlarges and develops into a fruit.

Question 3.
What is Asexual reproduction? Explain the spore formation in Rfiizoptis with a diagram.
Answer:
Production df an offspring by a single parent without the formation and fusion of gametes is called Asexual reproduction. Asexual reproduction occurs by spore formation. In Rhizopus, during spore formation, a structure called sporangium develops from the fungal hypha. The nucleus divides several times within the sporangium and each nucleus with a small amount of cytoplasm develops into a spore. The spores are liberated and they develop into new hypha after reaching the ground or substratum.

Question 4.
What could be the reasons for adopting contraceptive methods?
Answer:
Contraception is one of the best birth control measures. A number of techniques or method have been developed to prevent pregnancies in women which leads to welfare of the family group and society.

Question 5.
Explain the following:
(a) Toilet Hygiene
(b) Napkin Hygiene
(c) Menstrual Hygiene
Answer:
(a) Toilet Hygiene:

  • To reduce the bad odour and infection, the floors of the toilet should be kept clean and dry.
  • Toilet flush handles, doorknobs, light switches and walls should be cleaned with disinfectants to kill harmful germs and bacteria.
  • Hands should be washed with soap, before and after toilet use.

(b) Napkin Hygiene:

  • To prevent infections, the sanitary pad, and tampon should be wrapped and discarded properly.
  • Sanitary pad and tampon should not be flushed down the toilet.
  • Napkin incinerators are to be used properly for disposal of used napkins.

(c) Menstrual Hygiene:

  • Sanitary pads should be changed regularly, to avoid infections due to microbes from vagina and sweat from genitals.
  • Use of warm water to clean genitals helps to get rid of menstrual cramps.
  • Wear loose clothing, to have airflow around the genitals and prevent sweating.

Question 6.
Explain the structure of the following:
(a) Testes
(b) Ovary
Answer:
(a) Testes: Testes are the reproductive glands of the male, that are Oval shaped, which lie outside the abdominal cavity of a man, in a sac-like structure called Scrotum. Each testis is covered with a layer of fibrous tissue called tunica albuginea. Septa divides the testes into pyramidal lobules, in which lie seminiferous tubules, cells of Sertoli and the Leydig cells. The process of spermatogenesis takes place in the seminiferous tubules. The Sertoli cells are the supporting cells and provide nutrients to the developing sperms. The Leydig cells lie between the seminiferous tubules and secrete testosterone. It initiates the process of spermatogenesis.

(b) Ovary: Ovaries are located on either side of the lower abdomen, composed of two almond-shaped bodies, each lying near the lateral end of the fallopian tube. Each ovary has an outer cortex and an inner medulla. The cortex is composed of a network of connective tissue called stroma and is lined by the germinal epithelium. The epithelial cells called the granulosa cells to surround each ovum in the ovary together forming the primary follicle. As the egg grows larger, the follicle also enlarges and gets filled with the fluid and is called the Graafian follicle.

Question 7.
What do you know about the National Health Programme?
Answer:
To improve the reproductive health of the people, National Health Programmes such as,
(a) Family Welfare Programme:

  • Maternal and Child Health Care (MCH).
  • Immunization of mothers, infants and children.
  • Nutritional supplement to pregnant women and children.
  • Motivate couples to accept contraceptive methods and to have small family norms, which improve economic status, living status and quality of life.

(b) Reproductive and Child Health Care (RCH)

  • Pregnancy and childbirth.
  • Postnatal care of the mother and child.
  • Importance of breastfeeding.
  • Prevention of reproductive tract infections and sexually transmitted diseases.

Question 8.
What is gastrulation?
Answer:
The transformation of blastula into gastrula and the formation of primary germ layers (Ectoderm, Mesoderm and Endoderm) by rearrangement of the cells is called gastrulation.

Question 9.
What is implantation?
Answer:
The process of attachment of the blastocyst to the uterine wall (endometrium) is called implantation. The blastocyst (fertilized egg) reaches the uterus and gets implanted in the uterus. The fertilized egg becomes implanted in about 6 to 7 days after fertilization.

VII. Draw a labelled diagram of the following.

Question 1.
Cross Section of:
(a) Human testes
(b) Human ovary
Answer:
(a) Human testes:

(b) Human ovary:

VIII. Write the expansion for the following abbreviations.

Question 1.

  1. WHO
  2. RCH
  3. MCH
  4. STD
  5. IUD
  6. UTI
  7. LH
  8. FSH.

Answer:

  1. WHO – World Health Organization
  2. RCH – Reproductive and Child Health Care
  3. MCH – Maternal and Child Health Care
  4. STD – Sexually Transmitted Diseases
  5. IUD – Intra-Uterine Device
  6. UTI – Urinary Tract Infection
  7. LH – Luteinizing Hormone
  8. FSH – Follicle Stimulating Hormones.

IX. Answer the following in detail. Draw diagrams wherever necessary.

Question 1.
With the help of a neat labelled diagram, explain, how does fertilization take place in flowering plants.
Answer:
The mature pollen grain contains two cells, the vegetative and the generative cell. The vegetative cell contains a large nucleus. The generative cell divides mitotically and forms two male gametes.

Pollen grains reach the stigma and begin to germinate. Pollen grain forms a small tube-like structure called pollen tube, which emerges through the germ pore. The contents of the pollen grain move into the tube. The pollen tube grows through the tissues of the stigma and style and finally reaches the ovule through the micropyle.

The vegetative cell degenerates and the generative cell divides to form two sperms or male gametes. Tip of pollen tube bursts and the two sperms enter the embryo sac. One sperm fuses with the egg and this process is called Syngamy and forms a diploid zygote. The other sperm fuses with the secondary nucleus, which is called the Triple fusion, to form the primary endosperm nucleus, which is triploid in nature.

Since two types of fusion syngamy and triple fusion take place in an embryo sac, the process is termed as double fertilization. After triple fusion, primary endosperm nucleus develops into an endosperm, which provides food to the developing embryo. Later the synergids and antipodal cells degenerate.

Question 2.
With examples and with the help of a neat labelled diagram, explain the different types of vegetative reproduction of plants.
Answer:
Vegetative reproduction takes place through,
(i) Leaves:

In Bryophyllum, small plants grow at the leaf notches.

(ii) Stem:
In plants like, strawberry aerial weak stems, touch the ground and give adventitious roots and buds. The offspring becomes an independent plant, when it is detached from the parent plant.

(iii) Root: Tuberous roots are used to develop new plants, eg. Asparagus, Sweet potato.

(iv) Bulbils: In some plants, the flower bud, modifies into the globose bulb, which is called bulbils. When these bulbils fall on the ground they grow into new plants, eg. Agave.

(v) Fragmentation: The breaking of the filament into many fragments is called fragmentation. Each fragment having one cell will give rise to a new filament by cell division, eg. Spirogyra.

(vi) Fission:

The parent cell divides into two daughter cells and each cell develops into a new adult organism eg. Amoeba.

(vii) Budding:

Formation of a daughter individual from a small projection, the bud arising on the parent body is called budding, eg. Yeast.

(viii) Regeneration: The ability of the lost body parts of an individual organism to give rise to a whole new organism is called regeneration. Regeneration takes place by the specialized mass of cells, eg. Hydra and Planaria.

Question 3.
Explain the two types of pollination and write the advantages and disadvantages of the types of pollination.
Answer:
The two types of pollination are
(a) Self – pollination: The transfer of pollen grains from the anther to the stigma of the same flower or another flower borne on the same plant is called self – pollination.
eg. Hibiscus. Self – pollination is also called Autogamy.
Advantages of self – pollination:

  • Self – pollination is possible in certain bisexual flowers.
  • Flowers do not depend on agents for pollination.
  • There is no wastage of pollen grains.

Disadvantages of self – pollination:

  • The seeds are less in numbers.
  • The endosperm is minute, so the seeds produce weak plants.
  • New varieties of plants cannot be produced.

(b) Cross-pollination: The transfer of pollen grains from the anthers of a flower to the stigma of a flower on another plant of the same species is called Cross-pollination, eg. Apples, Grapes, Plum.
Advantages of Cross-pollination:

  • The seeds produced as a result of cross-pollination, develop and germinate properly and grow into better plants.
  • Cross-pollination leads to the production of new varieties.
  • More viable seeds are produced.

Disadvantages of Cross-pollination:

  • Pollination may fail due to the distance barrier.
  • More wastage of pollen grains.
  • It may introduce some unwanted characters.
  • Flowers depend on the external agencies for pollination.

Question 4.
Explain the structure of Human Sperm and Ovum with a neat labelled diagram.
Answer:
1. Structure of Human sperm:
The spermatozoa consist of a head, middle piece and tail. The sperm head is elongated and formed by the condensation of the nucleus. The anterior portion has a cap-like structure called acrosome, which contains an enzyme hyaluronidase, that helps the sperm to enter the ovum during fertilization. A short neck connects the head and middle piece, which comprises the centrioles. The middle piece contains the mitochondria which provides energy for the movement of tail. It brings about sperm motility, which is essential for fertilization.

2. Structure of Ovum:
The mature ovum or egg is spherical in shape, free of yolk and contains abundant cytoplasm and the nucleus. The ovum is surrounded by three membranes. The plasma membrane is surrounded by inner thin zona pellucida and an outer thick corona radiata, which is formed of follicle cells. The membrane forming the surface layer of the ovum is called the vitelline membrane. The fluid-filled space between zona pellucida and the surface of the egg is called perivitelline space.

Question 5.
Explain the Agents of cross-pollination.
Answer:
Cross – pollination takes place through the agency of animals, insects, wind and water.
(a) Pollination by the wind: The pollination with the help of wind is called Anemophily. The Anemophilous flowers produce an enormous amount of pollen grains, which are small, smooth, dry and light in weight. This kind of pollen can blow off at a distance of more than 1,000 km. The stigmas are large, protruding and hairy to trap the pollen grains, eg. Grasses and some Cacti.

(b) Pollination by insects: Pollination with the help of insects like honey bees, flies are called entomophily. These flowers are brightly coloured, have the smell and have nectar, to attract insects. The pollen grains are larger in size, and the exine is pitted and spiny, so it can easily adhere firmly on the sticky stigma. About 80% of the pollination by insects is carried by honey bees.

(c) Pollination by water: The pollination with the help of water is called hydrophily. This takes place in aquatic plants. Pollen grains are produced in large numbers. Pollen grains float on the surface of water till they land on the stigma of female flowers, eg. Hydrilla, Vallisneria.

(d) Pollination by Animals: When pollination takes place with the help of animals, it is called Zoophily. The flowers have bright colour, size and scent to attract animals, eg. Sunbird pollinates flowers of Canna, Gladioli etc., Squirrels pollinate flowers of silk cotton tree.

Question 6.
Explain the parts of a flower, with a neat labelled diagram.
Answer:
The flower is the reproductive organ of a flowering plant. A flower is a modified shoot. A flower consists of four whorls borne on the thalamus. The whorls are from outside. The parts of a typical flower are as follows:

(a) Calyx: Calyx consists of sepals, forms the outermost whorl. They are non-essential or accessory whorls. It protects the flower bud.

(b) Corolla: Corolla consists of petals, which are modified leaves. They are often brightly coloured and in different shapes to attract pollinators. They are non-essential or accessory whorls because they do not directly take part in the reproduction.

(c) Androecium:

Androecium is the male reproductive part of a flower and is called an essential whorl, as they take part directly in reproduction. The androecium is composed of stamens. Each stamen consists of a stalk called the filament and a small bag like structure called anther at the tip. The pollen grains are produced in the anther within the pollen sac.

Pollen grains are spherical and have a two-layered wall. The hard outer layer is exine, which has apertures, called Germpore. The inner thin layer is intine, which is continuous and made up of cellulose and pectin. Mature pollen grain contain two cells, the vegetative and generative cell. Vegetative cell contains a large nucleus. The generative cell divides, to form two male
gametes.

(d) Gynoecium:
Gynoecium is the female reproductive part of a flower. It is an essential whorl because they take part directly in reproduction. Gynoecium is made up of carpels. It has (a) Ovary (b) Style (c) Stigma. Ovary contains the ovules. The main part of the ovule is the nucellus and is enclosed by two integuments, Jk. leaving an opening called as micropyle. The ovule is attached to the ovary wall, by a stalk called Funiculus.

Question 7.
Explain the steps involved from fertilization to foetal development in human.
Answer:
Fertilization in human is internal and occurs in the Oviduct of the female genital tract. It takes place in the ampulla of the fallopian tube. An oocyte is alive for about 24 hours after it is released from follicle. The sperm enters into the ovum, fuses and forms a zygote, which is a fertilized ovum. This process is called fertilization.

(a) Cleavage and formation of Blastula: The first cleavage takes place about 30 hours after fertilization. Cleavage is a series of rapid mitotic divisions of the zygote, to form many-celled blastula (Blastocyst), which comprises an outer layer of smaller cells and inner mass of larger cells.

(b) Implantation: The blastocyst (fertilized egg) reaches the uterus and gets implanted. The process of attachment of the blastocyst to the uterine wall is called Implantation. The fertilized egg, implanted in about 6 to 7 days after fertilization.

(c) Gastrulation: After implantation, the transformation of blastula into Gastrula and the formation of primary germ layers (Ectoderm, Mesoderm and Endoderm) by rearrangement of the cells takes place, which is called Gastrulation.

(d) Organogenesis: The various organs of the foetus are established from the different germ layers, during Organogenesis.

(e) Formation of Placenta: Placenta is a disc-shaped structure, attached to the Uterine wall between the developing embryo and maternal tissues. It allows the exchange of food materials, diffusion of oxygen, excretion of nitrogenous wastes and elimination of carbon-di-oxide. The cord which connects the placenta with the foetus is called the umbilical cord.

(f) Pregnancy (Gestation): Embryo attains its development in the uterus. Gestation period of human is 280 days. During pregnancy the uterus expands up to 500 times of its normal size.

(g) Parturition (Child Birth): Oxytocin from the posterior pituitary stimulates the uterine contractions and provides force to expel the baby from the uterus, causing birth. Parturition is the expulsion of young one from the mother’s Uterus at the end of gestation.

(h) Lactation: The process of milk production after childbirth from the mammary glands of the mother is called lactation. Milk production from the mammary gland is stimulated by prolactin, a hormone secreted by anterior pituitary. The ejection of milk is stimulated by posterior pituitary hormone oxytocin.

Question 8.
What is population explosion? Explain the different ways of family planning.
Answer:
The sudden and rapid rise in the size of the human population is called the Population Explosion. Contraception: Contraception is one of the best birth control measures. The devices used for contraception are called contraceptive devices. The common contraceptive methods used to prevent pregnancy are as follows:

(a) Barrier methods: This method prevents the meeting of an ovum by the sperms. The entry of sperm is prevented into the female reproductive tract by a barrier.

  • Condom: Condom is made of thin rubber or latex sheath. Condom prevents deposition of sperms in the vagina. A condom protects against Sexually Transmitted Diseases (STD) like Syphilis and AIDS.
  • Diaphragm (Cervical cap): Vaginal diaphragm fitting into the vagina or a cervical cap fitting over the cervix. This prevents the entry of sperms into the uterus.

(b) Hormonal Methods: Hormonal preparations are in the form of pills or tablets (contraceptive pills). These hormones stop the release of an egg from the ovary.

(c) Intra – Uterine Devices (IUDs): The intrauterine device (IUD) are contraceptive devices, inserted into the uterus. Lippe’s Loop and Copper-T, made of copper and plastic are two synthetic devices, commonly used in India. This can remain for a period of 3 years. This reduces the sperm fertilizing capacity and prevents implantation.

(d) Surgical methods: Surgical contraception or sterilization techniques are terminal methods to prevent any pregnancy. This procedure in males is called as vasectomy (ligation of vas deferens) and in females, it is called tubectomy (ligation of fallopian tube). These are methods of permanent birth control.


Samacheer, Kalvi, 10th, sslc, Science, Solutions, Chapter 16 Plant and Animal Hormones, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
Gibberellins cause _____.
(a) Shortening of genetically tall plants
(b) Elongation of dwarf plants
(c) Promotion of rooting
(d) Yellowing of young leaves.
Answer:
(c) Promotion of rooting

Question 2.
The hormone which has positive effect on apical dominance is:
(a) Cytokinin
(b) Auxin
(c) Gibberellin
(d) Ethylene
Answer:
(b) Auxin

Question 3.
Which one of the following hormones is naturally not found in plants?
(a) 2, 4 – D
(b) GA3
(c) Gibberellin
(d) IAA.
Answer:
(a) 2, 4 – D

Question 4.
Avena coleoptile test was conducted by:
(a) Darwin
(b) N. Smit
(c) Paal
(d) F.W. Went
Answer:
(d) F.W. Went

Question 5.
To increase the sugar production in sugarcanes they are sprayed with _____.
(a) Auxin
(b) Cytokinin
(c) Gibberellins
(d) Ethylene.
Answer:
(d) Ethylene.

Question 6.
LH is secreted by:
(a) Adrenal gland
(b) Thyroid gland
(c) Anterior pituitary
(d) Hypothalamus
Answer:
(c) Anterior pituitary

Question 7.
Identify the exocrine gland _____.
(a) Pituitary gland
(b) Adrenal gland
(c) Salivary gland
(d) Thyroid gland.
Answer:
(c) Salivary gland

Question 8.
Which organ acts as both exocrine gland as well as endocrine gland?
(a) Pancreas
(b) Kidney
(c) Liver
(d) Lungs
Answer:
(a) Pancreas

Question 9.
Which one is referred to as “Master Gland”?
(a) Pineal gland
(b) Pituitary gland
(c) Thyroid gland
(d) Adrenal gland.
Answer:
(b) Pituitary gland

II. Fill in the blanks.

Question 1.
______ causes cell elongation, apical dominance and prevents abscission.
Answer:
Auxin.

Question 2.
______ is a gaseous hormone involved in abscission of organs and acceleration of fruit ripening.
Answer:
Ethylene.

Question 3.
____ causes stomatal closure.
Answer:
Abscisic acid.

Question 4.
Gibberellins induce stem elongation in _____ plants.
Answer:
Corn and Pea.

Question 5.
The hormone which has a negative effect on apical dominance is _____.
Answer:
Cytokinin.

Question 6.
Calcium metabolism of the body is controlled by _____.
Answer:
Parathormone.

Question 7.
In the Islets of Langerhans, beta cells secrete _____.
Answer:
Insulin.

Question 8.
The growth and functions of the thyroid gland are controlled by _____.
Answer:
Hormone T3 and T4

Question 9.
Decreased secretion of thyroid hormones in the children leads to _____.
Answer:
Cretinism.

III. Match the following.

Question 1.
(a) Match the Column I with Columns II and III.

Column IColumn IIColumn III
AuxinGibberella fujikuroiAbscission
EthyleneCoconut milkIntermodal elongation
Abscisic acidColeoptile tipApical dominance
CytokininChloroplastRipening
GibberellinsFruitsCell division

(b) Match the following hormones with their deficiency states.

HormonesDisorders
1. Thyroxine(a) Acromegaly
2. Insulin(b) Tetany
3. Parathormone(c) Simple goitre
4. Growth hormone(d) Diabetes insipidus
5. ADH(e) Diabetes mellitus

Answer:
(a)

Column IColumn IIColumn III
AuxinColeoptile tipApical dominance
EthyleneFruitsRipening
Abscisic acidChloroplastAbscission
CytokininCoconut milkCell division
GibberellinsGibberella fujikuroiIntermodal elongation

(b)
1. (c) Simple goitre
2. (e) Diabetes mellitus
3. (b) Tetany
4. (a) Acromegaly
5. (d) Diabetes insipidus

IV. State whether True or false, If false write the correct statement.

Question 1.
A plant hormone concerned with stimulation of cell division and promotion of nutrient mobilization is cytokinin.
Answer:
True.

Question 2.
Gibberellins cause parthenocarpy in tomato.
Answer:
True.

Question 3.
Ethylene retards senescence of leaves, flowers and fruits.
Answer:
False.
Correct Statement: Ethylene hastens the senescence of leaves, flowers and fruits.

Question 4.
Exophthalmic goitre is due to the over secretion of thyroxine.
Answer:
True.

Question 5.
The pituitary gland is divided into four lobes.
Answer:
False.
Correct Statement: The Pituitary gland is composed of two lobes and performs different functions.

Question 6.
Estrogen is secreted by corpus luteum.
Answer:
False.
Correct Statement: Estrogen is produced by the Graafian follicles of the ovary.

V. Assertion and Reasoning Questions

Direction: In each of the following questions a statement of assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Mark the correct statement as,
(a) If both A and R are true and R is the correct explanation of A
(b) If both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) Both A and R are false.

Question 1.
Assertion: Application of cytokinin to marketed vegetables can keep them fresh for several days.
Reason: Cytokinins delay senescence of leaves and other organs by mobilisation of nutrients.
Answer:
(d) Both A and R are false.

Question 2.
Assertion (A): Pituitary gland is referred to as “Master gland”.
Reason (R): It controls the functioning of other endocrine glands.
Answer:
(a) If both A and R are true and R is the correct explanation of A.

Question 3.
Assertion (A): Diabetes mellitus increases blood sugar levels.
Reason (R): Insulin decreases blood sugar levels.
Answer:
(a) If both A and R are true and R is the correct explanation of A.

VI. Answer in a word or sentence.

Question 1.
Which hormone promotes the production of male flowers in Cucurbits?
Answer:
Gibberellins promote the production of male flowers in Cucurbits.

Question 2.
Write the name of synthetic auxin.
Answer:
2, 4 Dichloro phenoxy Acetic Acid is the synthetic hormone.

Question 3.
Which hormone induces parthenocarpy in tomatoes?
Answer:
Gibberellins are efficient in the formation of seedless fruit, inducing parthenocarpy in tomatoes.

Question 4.
What is the hormone responsible for the secretion of milk in female after child birth?
Answer:
Prolactin stimulates the secretion of milk in female after child birth.

Question 5.
Name the hormones which regulate water and mineral metabolism in man.
Answer:
Antidiuretic or vasopressin hormone regulates water and mineral metabolism in man.

Question 6.
Which hormone is secreted during emergency situation in man?
Answer:
Adrenaline and Noradrenaline is secreted during emergency situation in man.

Question 7.
Which gland secretes digestive enzymes and hormones?
Answer:
The pancreas is exocrine and endocrine in nature. The exocrine pancreas secretes pancreatic juice which plays a role in digestion. The endocrine portion (Islets of Langerhans) secrete hormones.

Question 8.
What are the hormones secreted by the posterior lobe of the pituitary gland? Mention the tissues on which they exert their effect.
Answer:

  • Vasopressin or Antidiuretic hormone.
  • Oxytocin is the two hormones of the posterior lobe of the pituitary gland.

In kidney tubules, the vasopressin hormone increases the reabsorption of water. It reduces the loss of water through urine.
Oxytocin helps in the contraction of the smooth muscles of the uterus at the time of childbirth and ” milk ejection from the mammary gland after childbirth.

Question 9.
Why are thyroid hormones refered as personality hormone?
Answer:
Thyroid hormones are essential for normal, physical, mental and personality development. So, it is called as personality hormone.

Question 10.
Which hormone requires iodine for its formation? What will happen if the intake of iodine in our diet is low?
Answer:
The hormones secreted by the thyroid gland are:

  • Triiodothyronine (T3)1
  • Tetraiodothyronine or Thyroxin (T4), which need an amino acid tyrosine and Iodine for its formation.

If the intake of Iodine in our diet is low or due to the inadequate supply of iodine in our diet leads to the enlargement of the thyroid gland, which protrudes, as swelling in the neck and is called as goitre.

VIII. Long Answer Questions

Question 1.
(a) Name the gaseous plant hormone. Describe its three different actions in plants.
Answer:
Ethylene is a gaseous plant hormone.

  1. Ethylene promotes the ripening of fruits. Eg: Tomato, Apple, Mango, Banana, etc.
  2. Ethylene inhibits the elongation of stem and root in dicots.
  3. Ethylene hastens the senescence of leaves and flowers.

(b) Which hormone is known as a stress hormone in plants? Why?
Answer:
Abscisic acid increases the tolerance of plants to various kinds of stress. So, it is also called a stress hormone. It is found in the chloroplast of plants.

Question 2.
Describe an experiment which demonstrates that growth-stimulating hormone is produced at the tip of the coleoptile?
Answer:
Went’s experiment was done by Frits warm out. This experiment demonstrates the growth-stimulating hormone Auxin is produced at the tip of the coleoptile.

He did a series of experiments in Avena Coleoptiles. In his first experiment, he removed the tips of Avena coleoptiles. The cut tips did not grow, indicating that the tips produced something essential for growth.
In his second experiment, he placed the agar blocks on the decapitated coleoptile tips. The coleoptile tips did not show any response.

In his third experiment, he placed the detached coleoptile tips on agar blocks. After an hour, the tips were discarded and placed this agar block on the decapitated coleoptile. It grew straight up, indicating that some chemical had diffused from the cut coleoptile tips into the agar block, which stimulated the growth.

From these experiments, Went concluded that, the chemical diffusing from the tip of coleoptile was responsible for the growth and he named it as “Auxin”.

Question 3.
Write the physiological effects of gibberellins.
Answer:

  1. Application of gibberellins on plants stimulate extraordinary elongation of intemode. Eg: Com and Pea.
  2. Treatment of rosette plants with gibberellin induces sudden shoot elongation followed by flowering. This is called bolting.
  3. Gibberellins promote the production of male flowers in monoecious plants (Cucurbits).
  4. Gibberellins break dormancy of potato tubers.
  5. Gibberellins are efficient than. auxins in inducing the formation of seedless fruit – Parthenocarpic fruits (Development of fruits without fertilization) Eg: Tomato.

Question 4.
Where are estrogens produced? What is the role of estrogens in the human body?
Answer:
Estrogen, the female sex hormone is produced by the Graafian follicles of the ovary.
Role of estrogen:

  • It brings about the changes that occur during puberty.
  • It initiates the process of oogenesis.
  • It stimulates the maturation of ovarian follicles in the ovary.
  • It promotes the development of secondary sexual characters (breast development and high pitched voice, etc).

Question 5.
What are the conditions which occur due to lack of ADH and insulin? How are the conditions different from one another?
Answer:
ADH:
Deficiency of ADH causes a disorder called diabetes insipidus.
Deficiency of ADH reduces the reabsorption of water and causes an increase in urea output (polyuria). This deficiency disorder is called Diabetes insipidus.

IX. Higher Order Thinking Skills (HOTS) Questions

Question 1.
What would be expected to happen if,

  1. Gibberellin is applied to rice seedlings?
  2. A rotten fruit gets mixed with unripe fruits.
  3. When cytokinin is not added to the culture medium.

Answer:

  1. When gibberellins are applied, it stimulates, the extraordinary elongation of internodes.
  2. The mass of undifferentiated cell is called callus. If the rotten fruits get mixed with unripe fruits, then the ethylene produced from the rotten fruits will hasten the ripening of the unripe fruits.
  3. If cytokinin is not added to the culture medium, then the cell division, growth and differentiation will not be observed.

Question 2.
A plant hormone was first discovered in Japan when rice plants were suffering from Bakanae disease caused by Gibberella fujikoroi. Based on this information answer the following questions:
(a) Identify the hormone involved in this process.
Answer:
Gibberellin is involved in this process.

(b) Which property of this hormone causes the disease?
Answer:
It stimulates extraordinary elongation of intemode.

(c) Give two functions of this hormone.
Answer:

  1. Gibberellin break dormancy of potato tubers.
  2. Gibberellin promotes the production of male flower in monoecious plant (Cucurbits).

Question 3.
Senthil has high blood pressure, protruded eyeball and increased body temperature. Name the endocrine gland involved and hormone secretion responsible for this condition.
Answer:
The endocrine gland is Thyroid gland, and the hormones secreted are Triiodothyronine (T3) and Tetraiodothyronine or Thyroxine (T4). The excess secretion of the Thyroid hormone leads to Grave’s disease. The symptoms are protrusion of eyeballs (exophthalmia), increased metabolic rate, high body temperature, profuse sweating, loss of body weight and nervousness.

Question 4.
Sanjay is sitting in the exam hall. Before the start of the exam, he sweats a lot, with increased rate of heart beat. Why does this condition occur?
Answer:
It is due to secretion of Epinephrine and Norepinephrine as it produced during conditions of stress and emotion. They are called as “Emergency hormones” or flight, fright and fight hormone.

Question 5.
Susan’s father feels very tired and frequently urinates. After clinical diagnosis, he was advised to take an injection daily to maintain his blood glucose level. What would be the possible cause for this? Suggest preventive measures.
Answer:
The deficiency of insulin causes Diabetes mellitus. He has Diabetes mellitus. Increase in blood sugar level (Hyperglycemia). He was advised to take an injection, Insulin, which helps in the conversion of glucose into glycogen, which is stored in the liver. It decreases the concentration of glucose in the blood.
Preventive measures:

  • Manage the weight
  • Exercise regularly
  • Eat a balanced healthy diet
  • Limit alcohol intake
  • Quit smoking
  • Control the blood pressure

Textbook Activities Solved

Activity 1.
Place two or three unripe tomatoes in a brown paper bag with a ripe banana and roll the top closed. In another bag place two or three unripe tomatoes only and roll the top closed, Observe what happens to the tomatoes? Why?
Answer:
As the banana continues to ripen in the first bag, it produces ethylene gas. The gas trapped in the bag will cause tomatoes to ripen. The tomatoes remain unripe in the second bag.

Samacheer Kalvi 10th Science Plant and Animal Hormones

Additional Questions Solved

I. Fill in the blanks.

Question 1.
The chemical substances produced by plants are called _____.
Answer:
Hormones.

Question 2.
Tie two lobes of thyroid glands are connected by means of a narrow band of tissue called _____.
Answer:
Isthmus.

Question 3.
The chief cells of parathyroid glands are _____.
Answer:
Parathormone.

Question 4.
The other name for adrenal gland is _____.
Answer:
Supra Renal.

Question 5.
The hormones secreted by the adrenal cortex are _____.
Answer:
Corticosteroids

Question 6.
During water stress and drought conditions _______ causes stomatal closure.
Answer:
Abscisic acid.

Question 7.
Glucagon helps the break down of ______ to glucose in the liver.
Answer:
Glycogen.

Question 8.
The adrenal medulla is composed of ______ cells.
Answer:
Chromaffin.

Question 9.
The male sex hormone _______ is responsible for the development of secondary sexual characters.
Answer:
Testosterone.

Question 10.
_______ is a gaseous plant hormone, mainly concerned with maturation and ripening of fruits.
Answer:
Ethylene.

Question 11.
The other name for pituitary gland is _____.
Answer:
Hypophysis.

Question 12.
The glandular follicles of the thyroid gland are filled with colloid material called _____.
Answer:
Thyroglobulin.

II. Match the following.

Question 1.

1. Morphogenesis(a) Chromaffin cells
2. Bakanae disease(b) Male sex hormone
3. Still not cou(c) Thymus
4. Testosterone(d) Gibberella fujikuroi
5. Adrenal medulla(e) Female sex hormone
6. Thymosin(f) Callus in tissue culture
7. Estrogen(g) spasm

Answer:

  1. (f) Callus in tissue culture
  2. (d) Gibberella fujikuroi
  3. (g) Muscle spasm
  4. (b) Male sex hormone
  5. (a) Chromaffin cells
  6. (c) Thymus
  7. (e) Female sex hormone.

III. Choose the odd one out.

Question 1.
Auxins, Parthenocarpy, apical dominance, Parathormone?
Answer:
Parathormone.

Question 2.
Senescence, Dormancy, Estrogen, abscission?
Answer:
Estrogen.

Question 3.
Glucagon, Endocrine, Exocrine, Gibberellins?
Answer:
Gibberellins.

Question 4.
Norepinephrine, Isthmus, tyrosine, thyroglobulin?
Answer:
Norepinephrine.

Question 5.
Gonads, Thyroid, Cytokinin, Thymus?
Answer:
Cytokinin.

IV. Match the following endocrine glands with their location.

Question 1.

1. Pituitary gland(a) Female sex gland
2. Thyroid gland(b) Male sex gland
3. Parathyroid(c) Above the kidney
4. Islets of Langerhans(d) The posterior surface of the thyroid lobe
5. Adrenal gland(e) The upper part of the chest, the lower end of the trachea
6. Testes(f) Base of midbrain
7. Ovary(g) Pancreas
8. Thymus(h) Trachea

Answer:

  1. (f) Base of midbrain
  2. (h) Trachea
  3. (d) The posterior surface of the thyroid lobe
  4. (g) Pancreas
  5. (c) Above the kidney
  6. (b) Male sex gland
  7. (a) Female sex gland
  8. (e) The upper part of the chest, the lower end of Trachea.

V. Write ‘True’ or ‘False’ for the following statements. Write the correct statement for false:

Question 1.
Auxins, cytokinins and gibberellins inhibit plant growth, while abscisic acid and Ethylene promote plant growth.
Answer:
False.
Correct Statement: Auxins, cytokinins and gibberellins promote plant growth, while abscisic acid and ethylene inhibit plant growth.

Question 2.
Glucagon helps in the breakdown of glycogen to glucose in the liver.
Answer:
True.

Question 3.
The thymus is partly an endocrine gland and partly a lymphoid gland.
Answer:
True.

Question 4.
Leydig cells from the cells of a female. Gonads located in the pelvic cavity.
Answer:
False.
Correct Statement: Leydig cells from the endocrine part of the testes.

Question 5.
Cretinism is caused due to increased secretion of the thyroid hormones in children.
Answer:
False.
Correct Statement: Cretinism is caused due to decreased secretion of the thyroid hormones in children.

Question 6.
Cytokinin promotes the growth of lateral buds even in the presence of apical buds.
Answer:
True.

VI. Answer the following in a word or with a sentence.

Question 1.
Where are Auxins produced?
Answer:
Auxins are produced at the tip of stems and roots from where they migrate to the zone of elongation.

Question 2.
What is Richmond Lang effect?
Answer:
Delaying the process of ageing in plants with the application of cytokinin is called Richmond Lang effect.

Question 3.
What is Richmond Lang effect?
Answer:
Application of cytokinin delays the process of ageing in plants. This is called Richmond Lang effect.

Question 4.
Give the uses of progesterone.
Answer:
Progesterone maintains pregnancy and regulates the menstrual cycle.

Question 5.
What are the secretions of alpha and beta cells of Islets of Langerhans?
Answer:
Alpha cells secrete glucagon and beta cells secrete Insulin.

Question 6.
What is the main function of Glucogen.
Answer:
Glucogon converts excess amount of glycogen stored under the muscle and liver to glucose. Thus raising the blood glucose level.

Question 7.
Name the two types of sex glands.
Answer:
Testes and Ovaries.

Question 8.
Specify the symptoms of acromegaly.
Answer:
Acromegaly leads to abnormal enlargement of head, face, hand and feet.

Question 9.
Name the three layers of the adrenal cortex.
Answer:

  • Zona glomerulosa
  • Zona fasciculata
  • Zona reticularis

Question 10.
What is Endocrinology?
Answer:
The branch of biology which deals with the study of the endocrine glands is called Endocrinology.

VII. Answer the following briefly.

Question 1.
Name the types of plant hormones.
Answer:

  • Auxins
  • Cytokinins
  • Gibberellins
  • Abscisic acid
  • Ethylene.

Question 2.
Growth hormone is important for normal growth. Explain.
Answer:
Growth hormone promotes the development and enlargement of all tissues •of the body. It stimulates the growth of muscles, cartilage and long bones. It controls cell metabolism.

Question 3.
What are Ductless glands? Why are they called so?
Answer:
Endocrine glands are called ductless glands because their secretions are diffused into the bloodstream, and are carried to the different parts of the body. They do not have specific ducts to carry the hormones.

Question 4.
Why pancreas is called as dual gland?
Answer:
The exocrine part of the pancreas produces pancreatic juice. The endocrine part produce islets of Langerhans, consists of two cells namely alpha cells that produce a hormone called glucagon and Beta cells that produce insulin. So, it is called as dual gland.

Question 5.
Write any three physiological effects of cytokinins.
Answer:

  • Cytokinins induce cell division.
  • Cytokinins promote the growth of lateral buds even in the presence of apical buds.
  • Cytokinesis causes cell enlargement.

Question 6
Which gland is a link between endocrine and lymphoid gland.
Answer:
Thymus is partly an endocrine gland and partly a lymphoid gland. It is located in the upper part of the chest covering the lower end of trachea. Thymosin is the hormone secreted by the thymus.

Question 7.
What are the functions of thyroid hormones? Write any three points.
Answer:

  • Production of energy by maintaining the Basal Metabolic Rate (BMR) of the body.
  • Helps to maintain normal body temperature.
  • Influences the activity of the Central Nervous System.

Question 8.
What are plant hormones?
Answer:
Plant hormones are organic molecules that are produced at extremely low concentration in plants. These molecules control morphological, physiological and biochemical responses.

Question 9.
Explain any three functions of Testosterone.
Answer:

  • It influences the process of spermatogenesis.
  • It stimulates protein synthesis and controls muscular growth.
  • Responsible for the development of secondary sexual characters (distribution of hair on body and face and deep voice pattern, etc.).

Question 10.
Write a short note on the thymus gland.
Answer:
The thymus gland is partly an endocrine gland and partly a lymphoid gland. It is located in the upper part of the chest covering the lower end of the trachea. Thymosin is the hormone secreted by Thymus.
Functions:

  • It has a stimulatory effect on the immune function.
  • It stimulates the production and differentiation of lymphocytes.

VIII. Draw a labelled diagram for the following.

Question 1.
Hormonal interaction in plant growth and development.
Answer:

Question 2.
Pancreas
Answer:

Question 3.
Adrenal gland
Answer:

IX. Answer the following in detail.

Question 1.
With a neat labelled diagram, explain the pituitary gland and the types of hormones.
Answer:

The pituitary gland is a pea-shaped compact mass of cells located at the base of the midbrain. As it regulates and controls the other endocrine glands, it is called “Master gland”

1. Hormones secreted by anterior pituitary:
(a) Growth Hormone (GH): It promotes the development and enlargement of all tissues. It stimulates the growth of muscles, cartilage and long bones. It controls cell metabolism. Decreased secretion of growth hormone leads to Dwarfism in children characterised by stunted growth, delayed skeletal formation and mental disability. Oversecretion of growth hormone leads to gigantism in children. Characterised by abnormal enlargement of head, face, hands and feet.

(b) Thyroid Stimulating Hormone (TSH) – a growth of thyroid gland.

(c) Adrenocorticotrophic hormone (ACTH) – Protein synthesis in the adrenal cortex.

(d) Gonadotrophic hormones (GTH) – for the normal development of Gonads.
The other two hormones are Follicle Stimulating Hormone (FSH); Luteinizing Hormones (LH)

(e) Prolactin (PRL) Initiates the development of mammary glands during pregnancy and production of milk after childbirth.

2. Hormones secreted by the posterior lobe:
(a) Vasopressin or Antidiuretic hormone (ADH) – It reduces the loss of water through urine. Deficiency of ADH reduces the reabsorption of water and causes an increase in urine output (polyuria). This deficiency disorder is called Diabetes insipidus.

(b) Oxytocin – It helps in the contraction of the smooth muscles of the uterus at the time of childbirth and milk ejection from the mammary gland after childbirth.

Question 2.
With a neat labelled diagram, explain thyroid gland, functions of thyroid hormones and the thyroid dysfunction.
Answer:
The thyroid gland is composed of two distinct lobes lying one on either side of the trachea. The two lobes are connected by means of a narrow band of tissue called as the isthmus, the gland is composed of glandular follicles and lined by cuboidal epithelium. The follicles are filled with colloid material called thyroglobulin. An amino acid tyrosine and iodine are involved in the formation of thyroid hormone.
The hormones secreted by the thyroid gland are:

  1. Triiodothyronine (T3)
  2. Tetraiodothyronine or Thyroxine (T4)

Functions of Thyroid hormone:

  • Production of energy by maintaining the Basal Metabolic Rate (BMR) of the body.
  • Helps to maintain normal body temperature.
  • Influences the activity of the Central Nervous System.
  • Controls growth of the body and bone formation.
  • Essential for normal physical, mental and personality development. So it is called personality hormone.
  • Regulates cell metabolism.

When the thyroid gland fails to secrete the normal level of hormone, the condition is called thyroid dysfunction. It leads to the following conditions:
1. Hypothyroidism: It is caused due to the decreased secretion of the thyroid hormones.

  • Goitre: Goitre is caused due to the inadequate supply of iodine in our diet. It leads to the enlargement of the thyroid gland, protruded, marked swelling in the neck and is called goitre.
  • Cretinism: It is caused due to decreased secretion of thyroid hormone in children. The conditions are stunted growth, mental defect, lack of skeletal development and deformed bones. They are called as cretins.
  • Myxoedema: It is caused by the deficiency of thyroid hormone in adults. They are mentally sluggish, increase in body weight, puffiness of the face, hand etc.

2. Hyperthyroidism: It is caused due to the excess secretion of the thyroid hormone, which leads to Grave’s disease. The symptoms are protrusion of the eyeballs (Exopthalmia), increased metabolic rate, high body temperature, sweating, loss of body weight and nervousness.


Samacheer Kalvi, 10th, sslc, Science, Solutions, Chapter 15 Nervous System, tamilnadu board, biology,

I. Choose the Correct Answer.

Question 1.
Bipolar neurons are found in _______
(a) retina of eye
(b) cerebral cortex
(c) embryo
(d) respiratory epithelium
Answer:
(a) retina of eye

Question 2.
Site for processing of vision, hearing,memory, speech, intelligence and thought is:
(a) kidney
(b) ear
(c) brain
(d) lungs
Answer:
(c) brain

Question 3.
In reflex action, the reflex arc is formed by _______
(a) brain, spinal cord, muscle
(b) receptor, muscle, spinal cord
(c) muscle, receptor, brain
(d) receptor, spinal cord, muscle
Answer:
(b) receptor, muscle, spinal cord

Question 4.
Dendrites transmit impulse ……cell body and axon transmit impulse …….. cell body.
(a) away from, away from
(b) towards, away from
(c) towards, towards
(d) away from, towards
Answer:
(b) towards, away from

Question 5.
The outer most of the three cranial meninges is ______
(a) arachnoid membrane
(b) piamater
(c) duramater
(d) myelin sheath
Answer:
(c) duramater

Question 6.
There are ______ pairs of cranial nerves and ______ pairs of spinal nerves.
(a) 12, 31
(b) 31, 12
(c) 12, 13
(d) 12, 21
Answer:
(a) 12, 31

Question 7.
The neurons which carries impulse from the central nervous system to the muscle fibre:
(a) afferent neurons
(b) association neuron
(c) efferent neuron
(d) unipolar neuron
Answer:
(c) efferent neuron

Question 8.
Which nervous band connects the two cerebral hemispheres of brain?
(a) thalamus
(b) hypothalamus
(c) corpus callosum
(d) pons
Answer:
(c) corpus callosum

Question 9.
Node of Ranvier is found in ______
(a) muscles
(b) axons
(c) dendrites
(d) cyton
Answer:
(b) axons

Question 10.
Vomiting centre is located in:
(a) medulla oblongata
(b) stomach
(c) cerebrum
(d) hypothalamus
Answer:
(a) medulla oblongata

Question 11.
Nerve cells do not possess _______
(a) neurilemma
(b) sarcolemma
(c) axon
(d) dendrites
Answer:
(b) sarcolemma

Question 12.
A person who met with an accident lost control of body temperature, water balance, and hunger. Which of the following part of brain is supposed to be damaged?
(a) Medulla oblongata
(b) cerebrum
(c) pons
(d) hypothalamus
Answer:
(d) hypothalamus

II. Fill in the blanks.

Question 1.
______ is the longest cell in our body.
Answer:
Axon

Question 2.
Impulses travels rapidly in ______ neurons.
Answer:
Myelin sheath of

Question 3.
A change in the environment that causes an animal to react is called ______
Answer:
reactions or responses

Question 4.
_____ carries the impulse towards the cell body.
Answer:
Dendrites

Question 5.
The two antagonistic components of the autonomic nervous system are _____ and ______
Answer:
Sympathetic, Parasympathetic

Question 6.
A neuron contains all cell organelles except _______
Answer:
Golgi apparatus in axon

Question 7.
_____ maintains the constant pressure inside the cranium.
Answer:
Cerebrospinal fluid

Question 8.
______ and ______ increases the surface area of cerebrum.
Answer:
Gyri and Sulci

Question 9.
The part of the human brain which acts as a relay centre is _______
Answer:
Thalamus

III. State whether True or False, if false write the correct statement.

Question 1.
Dendrons are the longest fibres that conduct impulses away from the cell body.
Answer:
False
Correct Statement: Axons are the longest fibres that conduct impulses away from the cell body.

Question 2.
The sympathetic nervous system is a part of the central nervous system.
Answer:
False
Correct Statement: Sympathetic nervous system is a part of the autonomic nervous system.

Question 3.
Hypothalamus is the thermoregulatory centre of the human body.
Answer:
True

Question 4.
The cerebrum controls the voluntary actions of our body.
Answer:
True

Question 5.
In the central nervous system, myelinated fibres form the white matter.
Answer:
False
Correct Statement: In the central nervous system, two types of matter such as white matter or grey matter, is formed, with respect to the presence or absence of myelin sheath.

Question 6.
All the nerves in the body are covered and protected by meninges.
Answer:
False
Correct Statement: The brain is covered by three connective tissue membrane or meninges.

Question 7.
Cerebrospinal fluid provides nutrition to brain.
Answer:
True

Question 8.
Reflex arc allows the rapid response of the body to a stimulus.
Answer:
True

Question 9.
Pons helps in regulating respiration.
Answer:
True

IV. Match the following

Question 1.

1. Nissil’s granules(a) Forebrain
2. Hypothalamus(b) Peripheral Nervous system
3. Cerebellum(c) Cyton
4. Schwann cell(d) Hindbrain

Answer:
1. (c) Cyton
2. (a) Forebrain
3. (d) Hindbrain
4. (b) Peripheral Nervous system

V. Understand the assertion statement. Justify the reason given and choose the correct choice.

(a). Assertion is correct and Reason is wrong
(b). Reason is correct and the assertion is wrong
(c). Both assertion and reason are correct
(d). Both assertion and reason are wrong

Question 1.
Assertion: Cerebrospinal fluid is present throughout the central nervous system.
Reason: Cerebrospinal fluid has no such functions.
Answer:
(a) Assertion is correct and Reason is wrong

Question 2.
Assertion: Corpus callosum is present in space between the dura mater and pia mater. Reason: It serves to maintain constant intracranial pressure.
Answer:
(d) Both assertion and reason are wrong

VI. Short Answer Questions.

Question 1.
Define the stimulus.
Answer:
The changes in the environmental condition, that are detected by receptors present in the body are called stimulus.

Question 2.
Name the parts of the hind brain.
Answer:
Hind brain consists of cerebellum, pons and medulla oblongata.

Question 3.
What are the structures involved in the protection of the brain?
Answer:
The brain is covered by three connective tissue membrane or meninges.

  • Dura mater, which is the outermost thick fibrous membrane.
  • Arachnoid membrane, which is the middle thin vascular membrane providing a web-like cushion.
  • Pia mater, which is the innermost, thin delicate membrane richly supplied with blood. Meningeal membranes protect the brain from mechanical injury.

Question 4.
Give an example for conditioned reflexes.
Answer:
Common examples of conditioned reflexes are playing a musical instrument, tying shoelaces or the neck-tie without being attentive, watering of the mouth after seeing or smelling favourite food.

Question 5.
Which acts as a link between the nervous system and the endocrine system?
Answer:
The hypothalamus controls the secretion of hormones from the Anterior Pituitary gland and is an important link between the nervous system and the endocrine system.

Question 6.
Define reflex arc.
Answer:
The path along which the reflexive impulse travel is called reflex arc.
(OR)
The path way taken by nerve impulse to accomplish reflex action is called reflex arc.

VII. Differentiate between

Question 1.
Voluntary and involuntary actions.
Answer:

Voluntary ActionInvoluntary Action
1. The actions which are under the control of our will, eg. Eating, walking.1. The actions, which are not under our control, eg. Breathing, Heartbeat
2. Controlled by the brain.2. Controlled by the spinal cord.
3. Voluntary Action results in muscular action.3. Involuntary actions result in a muscular action or secretions of some glands.

Question 2.
Medullated and non-medullated nerve fibre.
Answer:

Medullated nerve fibreNon-medullated nerve fibre
1. Nerve fibre is covered by a protective sheath, called the Myelin sheath, which is covered by Neurilemma.1. Nerve fibre is covered by a single sheath, Neurilemma.
2. Nodes of Ranvier are present.2. Nodes of Ranvier are absent.
3. They appear white.3. They appear grey.
4. They carry nerve impulses, much faster than non-medullated nerve fibre.4. They carry nerve impulses, much slower than medullated nerve fibre.
5. They are present in the white matter of brain, spinal cord and in the cranial and spinal nerves.5. They are present in the grey matter of the brain and spinal cord and in the autonomic nerves.

VIII. Long Answer Questions.

Question 1.
With a neat labelled diagram explain the structure of a neuron
Answer:
Structure of Neuron: A neuron consists of three basic parts namely Cyton, Dendrites and Axon.

(a) Cyton: Cyton is called cell body or perikaryon. It has a central nucleus with abundant cytoplasm called neuroplasm. The cytoplasm has a large granular body called Nissl’s granules and the other cell organelles like mitochondria, ribosomes, lysosomes, and endoplasmic reticulum. Neurons do not have the ability to divide. Several neurofibrils are present in the cytoplasm that help in the transmission of nerve impulses to and from the cell body.

(b) Dendrites: These are the numerous branched cytoplasmic processes, that project from the surface of the cell body. They conduct nerve impulses, towards the cyton. The branched projections increase the surface area for receiving the signals from other nerve cells.

(c) Axon: The axon is a single, elongated, slender projections. The end of axon terminates as fine branches, which terminate into knob like swellings called synaptic knob.

The plasma membrane of axon is called axolemma, while the cytoplasm is called axoplasm. It carries impulses away from the cyton. The axons may be covered by a protein sheath called myelin sheath, which is further covered by a layer of Schwann cells called neurilemma.

Myelin sheath breaks at intervals, by depressions called Nodes of Ranvier. The region between the nodes is called an internode. Myelin sheath acts as an insulator and ensures the rapid transmission of nerve impulses.
A junction between synaptic knob of the axon of one neuron and dendron of next neuron is called Synaptic Junction. Information from one neuron can pass to another neuron through these junctions, with the release of chemicals known as neurotransmitters, from the synaptic knob.

Question 2.
Illustrate the structure and functions of the brain.
Answer:
A human brain is formed of three main parts forebrain, midbrain and hindbrain.
1. Forebrain: The forebrain is formed of Cerebrum and Diencephalon. The diencephalon consists of dorsal thalamus and ventral hypothalamus.
(a) Cerebrum: It is the largest portion and nearly forms two-third of the brain. The cerebrum is longitudinally divided into two halves, as of right and left cerebral hemispheres by a deep – cleft called median cleft. The two cerebral hemispheres are interconnected by thick band of nerve fibres called corpus callosum. The outer portion of each cerebral hemisphere is formed of grey matter and is called cerebral cortex.

The inner or deeper part is formed of white matter and is called cerebral medulla. The cortex is extremely folded forming elevations called gyri, with depressions between them termed as sulci, that increase the surface area. Each cerebral hemisphere is divisible into a frontal lobe, a parietal lobe, a temporal lobe and an occipital lobe. These lobes are also known as cerebral lobes.

(b) Thalamus: Thalamus present in the cerebral medulla is a major conducting centre for sensory and motor signalling. It acts as a relay centre.

(c) Hypothalamus: It lies at the base of the thalamus. It controls the secretions of hormones from the anterior pituitary gland.

2. Midbrain: It is located between thalamus and Hindbrain. The dorsal portion of the midbrain consists of four rounded bodies called corporaquadrigemina, that control visual and auditory (hearing) reflexes.

3. Hindbrain: It is formed of three parts Cerebellum, Pons and Medulla Oblongata.

  • Cerebellum: It is the second-largest part of the brain formed of two large-sized hemispheres and middle vermis.
  • Pons: It is a bridge of nerve fibre that connects the lobes of the cerebellum. It relays signals between the cerebellum, spinal cord, midbrain and cerebrum.
  • Medulla Oblongata: It is the posterior-most part of the brain, that connects the spinal cord and various parts of the brain.

Functions of Brain:

StructureFunctions
1. Cerebral cortexSensory perception, Intelligence, consciousness, control of voluntary functions, language, thinking, memory, decision making, creativity, reasoning and will power.
2. ThalamusActs as Relay Station.
3. HypothalamusTemperature control, anger, thirst, hunger, urination, the important link between the nervous system and endocrine glands, sleep, sweating, sexual desire, fear, water balance, blood pressure.
4. MidbrainVisual and Auditory reflexes.
5. CerebellumMaintenance of posture and balance, and co-ordinate voluntary muscle activity.
6. PonsRespiration and Role in the sleep-wake cycle.
7. Medulla OblongataCardiovascular, respiratory and digestive control centres, vasomotor centres to control heartbeat, contraction of blood vessels. It also regulates vomiting and salivation.

Question 3.
What will you do if someone pricks your hand with a needle? Elucidate the pathway of response with a neat labelled diagram.
Answer:

The pathway taken by nerve impulse to accomplish reflex action is called the reflex arc.

  • When the hand is pricked by a needle, the stimulus is the prick (touch) pain, which is sensed by a receptor called touch or pain receptors in the skin in our hand. This stimulus in tum triggers an impulse in a sensory neuron.
  • The sensory neuron transmits or conveys the message to the spinal cord.
  • The spinal cord interprets the stimulus and the impulse is passed on to the relay neuron, which in tum transmits it to a motor neuron.
  • Motor neurons carry command from the spinal cord to our arm.
  • The muscle in our arm contracts and we withdraw our hand immediately from the needle prick. Muscle is the effector organ which has responded to the prick (pain).

Question 4.
Describe the structure of the spinal cord.
Answer:
The spinal cord is a cylindrical structure lying in the neural canal of the vertebral column. It is also covered by meninges. It extends from the lower end of medulla oblongata to the first lumbar vertebra. The posterior-most region of spinal cord tapers into a thin fibrous thread-like structure called Filum terminate.

Internally, the spinal cord contains a cerebrospinal fluid-filled cavity, known as the central canal. The grey matter of the spinal cord is ‘H’ shaped. The upper end of the letter, ‘H’ forms posterior horns and lower end forms anterior horns. A bundle of fibres pass into the posterior horn forming the dorsal or afferent root. Fibres pass outward, from the anterior horn forming the ventral or efferent root. These two roots joins to form spinal nerves. The white matter is external and has a bundle of nerve tracts. Spinal cord conducts sensory and motor impulses to and from the brain. It controls the reflex actions of the body.

Question 5.
How nerve impulses are transferred from one neuron to next neuron?
Answer:
All the information from the environment is detected by the receptors, located in the sense organs such as the eyes, nose, skin and etc. Information from the receptors is transmitted as electrical impulse and is received by the dendritic tips of the neuron. This impulse travels from the dendrite to the cell body and then along the axon to its terminal end. On reaching the axonal end, it causes the nerve endings to release a chemical (neurotransmitter) which diffuses across a synapse and starts a similar electrical impulse in the dendrites of the next neuron, then to their cell body to be carried along the axon.

The electrical signal reaches the brain or spinal cord. The response from the brain (or spinal cord) is similarly passed on to the effector organs such as the muscle or gland cell, that undergoes the desired response.

Question 6.
Classify neurons based on its structure.
Answer:
The neurons are classified, based on their structures:

(a) Unipolar neurons: Only one nerve process arises from the cyton, which acts as both axon and dendron. It is found in early embryos, but not in the adult.

(b) Bipolar neurons: The cyton gives rise to two nerve processes, of which one acts as an axon, while another acts as a dendron. Bipolar neurons are found in the retina of the eye and olfactory epithelium of nasal chambers.

(c) Multipolar neurons: The cyton gives rise to many dendrons and an axon. Multipolar neurons found in the cerebral cortex of the brain.

IX. Higher Order Thinking Skills (HOTS) Questions

Question 1.
‘A’ is a cylindrical structure that begins from the lower end of medulla and extend downwards. It is enclosed in bony cage ‘B’ and covered by membranes ‘C’ As many as ‘D’ pairs of nerves arise from the structure ‘A’.

  1. What is A?
  2. Name (a) bony cage ‘B’ and (b) membranes ‘C’
  3. How much is D?

Answer:

  1. A is spinal cord.
  2. (a) Bony cage is Vertebral column
    (c) is Meninges
  3. D is 31 pairs of spinal nerve.

Question 2.
Our body contains a large number of cells ‘L’ which are the longest cells in the body. L has a long and short branch called as ‘M’ and ‘N’ respectively. There is a gap ‘O’ between two ‘L’ cells, through which nerve impulse transfer by the release of chemical substance ‘P’.

  1. Name the cells L
  2. What are M and N?
  3. What is gap O?
  4. Name the chemical substance P?

Answer:

  1. Neuron
  2. Axon and Dendrites
  3. Synaptic Junction (knob)
  4. Neurotransmitter (Acetylcholine)

Samacheer Kalvi 10th Science Nervous System

Additional Questions Solved

I. Fill in the blanks.

Question 1.
The condition needed for the coordination between the various cells and organ for the diverse activities is called _____
Answer:
Homeostasis

Question 2.
A number of nerve fibres bundled up together to form _____
Answer:
Nerves

Question 3.
The other name for cyton is cell body or _____
Answer:
Perikaryon

Question 4.
______ is an important neurotransmitter released by neurons.
Answer:
Acetylcholine

Question 5.
_______ membranes protect the brain from mechanical injury.
Answer:
Meningeal

Question 6.
The four rounded bodies of the midbrain are called ______
Answer:
Corporaquadrigemina

Question 7.
The Posterior most region of spinal cord tapers into fibrous thread-like structures called _____
Answer:
Filum terminale

II. Choose the incorrect statement and Write it as a correct statement.

Question 1.
Responses refer to the changes in the environmental conditions, which are detected by receptors.
Answer:
Incorrect Statement
Correct Statement: Stimulus refer to the changes in the environmental conditions, which are detected by receptors. .

Question 2.
The brain is the controlling centre of all the body activities.
Answer:
Correct Statement

Question 3.
Axon carries impulses towards the cyton.
Answer:
Incorrect Statement
Correct Statement: Axon carries impulses away from the cyton.

Question 4.
CNS consists of all nerves, which connect the brain and spinal cord to all parts of the body.
Answer:
Incorrect Statement
Correct Statement: CNS consists of all nerves, which connect the brain and spinal cord to all parts of the body.

Question 5.
A receptor is a cell or group of cells that receive the stimuli.
Answer:
Correct Statement

III. Match the following.

Question 1.

1. Neuroglia(a) Conduct nerve impulses
2. Electrical impulse(b) Connects the lobe of the cerebellum
3. Pons(c) Cerebrospinal fluid
4. Brain(d) Do not conduct nerve impulses
5. Dendrites(e) Information from the receptor

Answer:
1. (d) Do not conduct nerve impulses
2. (e) Information from the receptor
3. (b) Connects the lobe of the cerebellum
4. (c) Cerebrospinal fluid
5. (a) Conduct nerve impulses

IV. Answer the following in a word or with a Sentence.

Question 1.
What are Spinal Reflexes?
Answer:
Most of the reflex actions are monitored and controlled by the spinal cord. So it is called Spinal Reflexes.

Question 2.
Name the two enlargement found in spinal cord.
Answer:
The spinal cord has two enlargements.
Cervical plexus – found in neck region
Lumbar plexus – in Lumbar region.

Question 3.
What is the function of Meningeai membranes in the brain?
Answer:
Meningeal membranes protect the brain from mechanical injury.

Question 4.
Write a function of glial cells.
Answer:
Glial cells or Neuroglia are non-exciting, supporting cells of nervous system.

Question 5.
Name the granules in the cytoplasm of Peyton.
Answer:
Nissl’s granules.

Question 6.
Which is the controlling centre of all body activities?
Answer:
Brain

Question 7.
In which fluid, is the brain suspended?
Answer:
The brain is suspended in the cerebrospinal fluid.

Question 8.
Name the four rounded bodies in the dorsal portion of midbrain.
Answer:
Corpora quadrigemina

Question 9.
Which is the longest cell of the human body?
Answer:
The longest cell of the human body is axon.

Question 10.
Name the tapered spinal cord into a thin thread-like structure present in the posterior-most region.
Answer:
Filum terminate.

V. Draw a neat labelled diagram of the following.

Question 1.
(a) Brain
(b) Structure of Spinal Cord
(c) Nerve impulse transmission
Answer:
(a) Brain

(b) Structure of Spinal Cord

(c) Nerve impulse transmission

VI. Answer the following briefly.

Question 1.
What is the synaptic transmission?
Answer:
The flow of nerve impulses from the axonal end of one neuron to the dendrite of another neuron through a synapse is called synaptic transmission.

Question 2.
What is homeostasis?
Answer:
The coordination between the various cells and organs is essential for their diverse activities to maintain physiological balance called Homeostasis.

Question 3.
What are Neurotransmitters? Give an example.
Answer:
Neurotransmitters are chemicals, which allow the transmission of a nerve impulse from the axon terminal of one neuron to the dendron of another neuron or to an effector organ. Acetylcholine is the neurotransmitter released by neurons.

Question 4.
Name the three connective tissue membrane of Meninges.
Answer:

  1. Duramater : Outermost thick fibrous membrane.
  2. Arachnoid membrane : Middle thin vascular membrane provide web like cushion.
  3. Piamater : Innermost thin oblicate membrane richly supplied with blood.

Question 5.
What are the types of nerve fibres?
Answer:
The two types of nerve fibres, based on the presence or absence of myelin sheath are

  • Myelinated nerve fibre: The axon is covered with a myelin sheath.
  • Non-myelinated nerve fibre: The axon is not covered by a myelin sheath.

Myelinated and non-myelinated nerve fibres from the white matter and grey matter of the brain.

Question 6.
Why is the Autonomic Nervous System called Visceral nervous system?
Answer:
The Autonomic Nervous System is also called Visceral Nervous System because it regulates the function of internal visceral organs of our body.

Question 7.
What are the cerebral lobes?
Answer:
Each cerebral hemisphere is divisible into a frontal lobe, a parietal lobe, a temporal lobe and an occipital lobe. These lobes are called cerebral lobes.

Question 8.
How are neurons categorized on the basis of functions?
Answer:
On the basis of functions the neurons are categorised as:

  • Sensory or afferent neurons, which carry impulses from the sense organ to the central nervous system.
  • Motor or efferent neurons, which carry impulses from the central nervous system to effector organs such as the muscle fibre and the gland.
  • Association neurons, which conduct impulses between sensory and motor neurons.

Question 9.
What is cerebrospinal fluid? What is its functions?
Answer:
The brain is suspended in a special fluid environment called cerebrospinal fluid (CSF).
Functions:

  • It acts as a shock-absorbing fluid and protects the brain from damage when it is subjected to a sudden jerk.
  • It supplies nutrients to the brain.
  • It collects and removes wastes from the brain.
  • It is responsible for maintaining a constant pressure inside the cranium.

Question 10.
Explain the Peripheral Nervous System.
Answer:
Peripheral Nervous System is formed, by the nerves arising from the brain and the spinal cord. The nerves arising from the brain are called cranial nerves. In man, there are 12 pairs of cranial nerves. Some of the cranial nerves are sensory.
Nerves arising from the spinal cord are called spinal nerves. In man, there are 31 pairs of spinal nerves. Each spinal nerve has a dorsal sensory root and the ventral motor root.

VI. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Raju got an injury on the head during motorbike accident on the road. Later he faced a problem in maintaining balance of the body while walking or sitting. Which part of the brain do you think is affected?
Answer:
Cerebellum in the brain is affected as it maintains the body balance.

Question 2.
What is Electroencephalogram (EEG)?
Answer:
Electroencephalogram (EEG) is an instrument, which records the electrical impulses of the brain. An EEG can detect abnormalities in the brain waves and help in diagnoses of epilepsy, brain tumours and head injuries, etc.

Question 3.
Name a few brain diseases.
Answer:

  • Alzheimer’s disease (develop, as we age)
  • Parkinson’s disease
  • Amyotrophic Lateral Sclerosis (ALS)

Question 4.
What are brain injuries? Give examples.
Answer:
The damage of brain tissue, neurons and nerves. This damage affects our brain’s ability to communicate with the rest of our body. Examples of Brain injuries include blood clots, hematomas, swelling inside the skull, strokes and etc.

Question 5.
What are the symptoms of brain injury?
Answer:
Vomiting, Nausea, Speech difficulty, bleeding from the ear, Numbness and etc.


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