NCERT Exemplar Class 8 Science Solutions for Chapter 9 - Reproduction In Animals

NCERT Exemplar Class 8 Science Solutions for Chapter 9 - PDF Download Free Download

NCERT Exemplar for Class 8 Science Chapter 9 Reproduction in Animals is a perfect tool for your CBSE class 8 examination. This exemplar solution will make you learn the concept comprehensively by giving you extra knowledge. By solving this Exemplar question you will be able to clear all the doubts that can come on your mind.

NCERT Exemplar for Class 8 Science Chapter 9 will benefit you immensely as these solutions make you understand the topic thoroughly. This will lay a strong foundation for the advanced topic to be studied in the future. This exemplar has a variety of questions and answers on which you can rely on for your exam preparation.

The chapter reproduction in animals is about learning the different modes of reproduction like sexual reproduction and asexual reproduction. In sexual reproduction part, the students will learn about male reproductive organ, female reproductive organ, and fertilization. In asexual reproduction part, the students will learn about budding and binary fission. To score good marks in the exam students are advised to solve the questions from NCERT exemplar for class 8 chapter 9 reproduction in animals.

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Access Answers of NCERT Exemplar Class 8 Science Solutions for Chapter 9 – Reproduction In Animals

Multiple Choice Questions

1. Sets of reproductive terms are given below. Choose the set that has an incorrect combination.

(a) sperm, testis, sperm duct, penis

(b) menstruation, egg, oviduct, uterus

(c) sperm, oviduct, egg, uterus

(d) ovulation, egg, oviduct, uterus

Soln:

(c) sperm, oviduct, egg, uterus

Explanation:

Sperm is male gamete, egg is female gamete, oviduct and uterus are part of female reproductive system. Hence option c) is incorrect combination.

2. In humans, the development of fertilised egg takes place in the

(a) ovary

(b) testis

(c) oviduct

(d) uterus

Soln:

Answer is (d) uterus

Explanation:

The development of fertilised egg takes place in the uterus. Embryo gets embeeded in the wall of uterus for development by implantation.

3. In the list of animals given below, hen is the odd one out.

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 1

The reason for this is

(a) it undergoes internal fertilisation.

(b) it is oviparous.

(c) it is viviparous.

(d) it undergoes external fertilisation.

Soln:

Answer is (b) it is oviparous

Explanation:

Hen is oviparous , it lays egg and the young one gets hatched later.

Rest of the animals provided are viviparous. They give birth to young ones after they are developed completely.

4. Animals exhibiting external fertilisation produce a large number of gametes. Pick the appropriate reason from the following.

(a) The animals are small in size and want to produce more offsprings.

(b) Food is available in plenty in water.

(c) To ensure better chance of fertilisation.

(d) Water promotes production of large number of gametes.

Soln:

Answer is (c) To ensure better chance of fertilization

Explanation:

Because they release gametes in water chances of getting washed away by water, wind and rain are more. Hence To ensure better chance of fertilisation. Large number of gametes are produced by Animals exhibiting external fertilization.

5. Reproduction by budding takes place in

(a) hydra

(c) paramecium

(b) amoeba

(d) bacteria

Soln:

Answer is (a) hydra

Explanation:

Paramecium, Amoeba and bacteria reproduce by binary fission. Hydra reproduce by budding where a bud detacthes from the parent which grows into complete organism.

6. Which of the following statements about reproduction in humans is correct?

(a) Fertilisation takes place externally.

(b) Fertilisation takes place in the testes.

(c) During fertilisation egg moves towards the sperm.

(d) Fertilisation takes place in the human female.

Soln:

(d) Fertilisation takes place in the human female.

Explanation:

Male gametes are introduced into female’s body through vagina. Sperm reach uterus through oviduct. At uterus egg gets fertilized by sperm to form a zygote.

7. In human beings, after fertilisation, the structure which gets embedded in the wall of uterus is

(a) ovum

(b) embryo

(c) foetus

(d) zygote

Soln:

Answer is zygote

Explanation:

Egg fuses with sperm to form the zygote which will divide to form a clump of hundreds of cells which form the embryo. The process of moving down embryo from oviduct into uterus is call as implantation.

8. Aquatic animals in which fertilisation occurs in water are said to be:

(a) viviparous without fertilisation.

(b) oviparous with external fertilisation.

(c) viviparous with internal fertilisation.

(d) oviparous with internal fertilisation.

Soln:

Answer is (b) oviparous with external fertilisation.

Explanation:

Aquatic animals lay eggs and release sperms into water for fertilization to take place. Young one is formed outside the body hence it is called external fertilization.

9. After fertilisation, the resulting cell which gives rise to a new individual is the

(a) embryo

(b) ovum

(c) foetus

(d) zygote

Soln:

Answer is (d) zygote

Explanation:

Zygote is the beginning of formation of a new individual. All the multicellular organisms start their life from single celled zygote.

10. In human beings, the correct sequence of events during reproduction is

(a) gamete formation, fertilisation, zygote, embryo

(b) embryo, zygote, fertilisation, gamete formation

(c) fertilisation, gamete formation, embryo, zygote

(d) gamete formation, fertilisation, embryo, zygote

Soln:

Answer is (a) gamete formation, fertilisation, zygote, embryo

Explanation:

In humans male gametes fuse with female gametes to fertilise in the female ovary. Fertilised sperm and egg form zygote which will divide repeatedly to form the embryo.

Very Short Answer Questions

11. Although 2 cells called gametes fuse, the product formed is a single cell called zygote. Justify.

Soln:

During fertilization only nucleus of the sperm gets implanted into uterus to form zygote. Then sperm degenerates. Hence fused cell is called gamete.

Stages in the lifecycle of silkworm are given below. Write them in sequential order.

12. Stages in the lifecycle of silkworm are given below. Write them in sequential order.

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 2

Soln:

a)Egg

b)Pupa

c)Silkmoth

d)Silkworm

13. What is the importance of reproduction?

Soln:

Reproduction ensures continuation of species from generation to generation.

14. In markets, eggs of birds are available but never eggs of dogs. Why?

Soln:

Because dog is vivaparous. It does not lay egg. It gives birth to a new one.

15. The eggs of frogs do not have shells for protection, yet they are safe in water. How?

Soln:

Jelly like covering on the eggs give the protection Hence frog’s eggs are safe in water.

Short Answer Questions

16. Fill up the blanks with the terms given below:

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 3

Amoeba is a ___________ celled organism. It reproduces by ___________ reproduction. The process of reproduction begins by the division of its ___________ into two. This is followed by the division of its ___________ into two. This type of reproduction is called ___________ fission.

Soln:

Amoeba is a single celled organism. It reproduces by asexual reproduction. The process of reproduction begins by the division of its nucleus into two. This is followed by the division of its body into two. This type of reproduction is called binary fission.

17. The term metamorphosis is not used while describing human development. Why?

Soln:

Because body parts of humans will be present by birth. Whereas in metamorphosis parts of adults are different from the young ones.

18. Mother gives birth to a baby but the baby has characters of both parents. How is this possible?

Soln:

Though mother gives birth to a baby but fertilization involves fusion of gametes from both the parents. Hence character are obtained by both the parents.

19. How is reproduction in hydra different from that in amoeba?

Soln:

Hydra reproduce by budding where a bud detacthes from the parent which grows into complete organism. Whereas amoeba reproduces by binary fission. The process of reproduction begins by the division of its nucleus into two. This is followed by the division of its body into two.

20. State whether the following statements are True or False. If false, correct the statement:

(a) External fertilisation can occur both in water and on land.

(b) The eggs of fish are covered by hard shells for protection.

(c) Human egg has a head, middle piece and tail.

(d) In adult human females, a single mature egg is released into an oviduct every month.

Soln:

  1. False- External fertilisation can occur only in water.
  2. False- eggs of fish are covered by jelly like substance for protection.
  3. False- Human sperm has a head, middle piece and tail.
  4. True

21.Why do only male gametes have a tail?

Soln:

Because sperm need to be motile to reach non-motile egg in the ovary of female.

22. What does Fig. 9.1 represent?

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 4

Soln:

Figure shows Binary fission of amoeba with dividing nucleus.

23. Observe the figure given as Fig. 9.2 and answer the questions that follow.

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 5

(a) Label A and B.

(b) Identify the process.

(c) What happens during this process and what is formed?

Soln:

(a) A-sperm; B-ovum (egg)

(b) Fertilisation

(c) Sperm nucleus fuses with the egg nucleus to form the zygote.

Long Answer Questions

24. How can we say that fish exhibits external fertilisation?

Soln:

Female fish releases eggs into water and male fish releases sperm into water. Sperm swim randomly in water to reach egg. Nucleus of the sperm reaches egg and fuses to form the zygote. Since fertilization takes place externally. It is called external fertilization.

25.

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 6

After observing Fig. 9.3 answer the following.

a)

Read the following statements and label them in the figure:

  1. The part which produces female gametes.
  2. The part where development of the baby takes place.
  3. The part through which the developing embryo passes to reach the uterus.

b.

iv) Explain the future development of the embryo that would take place after it gets embedded in the uterus.

Soln:

a)

  1. Ovary
  2. Uterus
  3. Oviduct

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 7

b)

iv)

 

Developing embryo gets embedded in the wall of the uterus for further development. The embryo continues to develop in the uterus. It gradually develops body parts such as hands, legs, head, eyes, ears etc. The stage of the embryo in which all the body parts can be identified is called a foetus (Fig. 9.9). When the development of the foetus is complete, the mother gives birth to the baby.

26. Hens and frogs are both oviparous exhibiting different types of fertilisation. Explain.

Soln:

In Hens internal fertilisation takes place. Fertilised egg develops inside female body but development of chick from the embryo takes place outside the body.

On the other hand in frogs both fertilisation and development of zygote to embryo and young ones occurs outside the body.

27. Observe the following figures.

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 8

NCERT Exemplar Class 8 Science chapter 9 Solutions fig 9

  1. Identify the stages a to d in Fig. 9.4 during development of human baby.
  2. Arrange the stages in correct sequence of development.
  3. Explain the development that takes place in any one stage.

Soln:

(i)

(a) Embedding of the embryo in the uterus.

(b) Fertilisation.

(c) Zygote formation and development of an embryo from

the zygote.

(d) Zygote showing fusion of nuclei.

(ii) The correct sequence is

c, b, d, a

(iii) Zygote formation

The sperm and the egg nuclei fuses to form a single nucleus resulting in the formation of a fertilised egg or zygote.

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Also Read

Frequently Asked Questions on Reproduction In Animals

How is reproduction in hydra different from that in amoeba ?

Hydra reproduce by budding where a bud detacthes from the parent which grows into complete organism. Whereas amoeba reproduces by binary fission. The process of reproduction begins by the division of its nucleus into two. This is followed by the division of its body into two.

How is this possible when Mother gives birth to a baby but the baby has characters of both parents ?

Though mother gives birth to a baby but fertilization involves fusion of gametes from both the parents. Hence character are obtained by both the parents.

Why does the term metamorphosis is not used while describing human developmen ?

Because body parts of humans will be present by birth. Whereas in metamorphosis parts of adults are different from the young ones.

The eggs of frogs do not have shells for protection, yet they are safe in water. How?

Jelly like covering on the eggs give the protection Hence frog’s eggs are safe in water.

What is the importance of reproduction?

Reproduction ensures continuation of species from generation to generation.

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