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

Answer: (c) sperm, oviduct, egg, uterus

[ Sperm is a male reproductive cell, so it cannot be part of the female reproductive pathway involving oviduct and uterus.]

2. In humans, the development of fertilised egg takes place in the
(a) ovary     (b) testis     (c)  oviduct     (d) uterus

Answer: (d) uterus

[ In humans, the fertilised egg gets implanted and develops into an embryo in the uterus, where it receives nourishment and protection for proper growth.]

3. In the list of animals given below, hen is the odd one out. ‘‘ human being, cow, dog, hen ’’
The reason for this is
(a) it undergoes internal fertilisation.
(b) it is oviparous.
(c) it is viviparous.
(d) it undergoes external fertilisation.

Answer: (b) it is oviparous

[ Hen is the odd one because it lays eggs (oviparous), while humans, cow, and dog give birth to young ones (viviparous).]

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.

Answer: (c) To ensure better chance of fertilisation

[ External fertilisation occurs in water, where gametes may get wasted or destroyed, so producing many gametes increases the chance of successful fertilisation.]

5. Reproduction by budding takes place in
(a) hydra      (b) amoeba       (c) paramecium       (d) bacteria

Answer: (a) hydra 

[ Hydra reproduces by budding, where a new individual grows from a bud on the parent's body and later detaches.]
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.

Answer: (d) Fertilisation takes place in the human female 

[ In humans, fertilisation occurs internally inside the female's oviduct, not externally or in testes.]

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

Answer: (b) embryo

[ After fertilisation, the zygote divides repeatedly to form an embryo, which then gets embedded in the wall of the uterus.]

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.

Answer: (b) oviparous with external fertilisation .

[ Aquatic animals like fish and frogs lay eggs (oviparous), and fertilisation occurs outside the body in water.]

9. After fertilisation, the resulting cell which gives rise to a new individual is the
(a) embryo       (b) ovum      (c) foetus     (d) zygote

Answer: (d) zygote

[ The zygote is the single cell formed by the fusion of male and female gametes after fertilisation, which then develops into a new individual.]

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.

Answer: (a) gamete formation, fertilisation, zygote, embryo.

[ Gametes form first, then fertilisation produces a zygote, which develops into an embryo.]

VERY SHORT ANSWER QUESTIONS

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

Answer: Gametes (sperm and egg) fuse during fertilisation, but their nuclei combine to form one cell. This single cell is called a zygote, which later develops into a new organism.

12. Stages in the lifecycle of silkworm are given below. Write them in sequential order.
                  pupa, silkworm, egg, silkmoth

Answer: The sequential order is: egg → silkworm → pupa → silkmoth.

First, eggs hatch into silkworm larvae, then they form pupa inside cocoon, and finally emerge as adult silkmoth.

13. What is the importance of reproduction?

Answer: Reproduction is important because it produces new individuals of the same species. It helps in continuation of species, prevents extinction and passes genetic traits from parents to offspring.

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

Answer: Eggs of birds are available in markets because birds are oviparous (they lay eggs, which develop outside the mother's body). Dogs are viviparous (they give birth to live young ones after internal development), so they do not lay eggs.

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

Answer: The eggs of frogs are safe in water because they are covered by a protective gel-like coating. This coating prevents the eggs from drying out, protects them from small predators, and helps them stick to aquatic plants for support.

SHORT ANSWER QUESTIONS

16. Fill up the blanks with the terms given below:   body, asexual, binary, single, nucleus
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.

Answer: 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?

Answer: Metamorphosis is used when an organism shows sudden, major change in body form during its life cycle. Humans do not show such drastic change; they grow gradually from baby to adult, so the term is not used.

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

Answer: During fertilisation, sperm from father and egg from mother fuse to form zygote. This zygote carries genetic material from both parents, so the baby shows characters of both mother and father.

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

Answer: Hydra reproduces by budding, where a small outgrowth develops into a new organism. Amoeba reproduces by binary fission, where the whole body splits into two equal daughter cells.

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.

Answer: (a) False – External fertilisation occurs only in water, not on land.
(b) False – The eggs of fish are not covered by hard shells; they are covered by a thin, soft membrane for protection.
(c) False – Human egg does not have a head, middle piece, or tail; that structure describes a human sperm.
(d) True – In adult human females, a single mature egg is released into an oviduct every month.

21. Why do only male gametes have a tail?

Answer: Male gametes (sperms) have a tail called flagellum to help them move actively through fluids to reach the egg for fertilisation.

22. What does Fig. 9.1 represent?

   

Answer: The given figure represents a zygote. It shows the process of fertilisation, where the nucleus of a sperm and the nucleus of an egg fuse to form a single cell. This single cell is the beginning of a new individual.

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

                   Fig. 9.2

(a) Label A and B.
(b) Identify the process.
(c) What happens during this process and what is formed?

Answer: (a)  A – Sperm (the male gametes) .

B – Ovum of Egg cell (the female gamete) .

(b) The process show in the figure is fertilization .

(c) During fertilisation, the nucleus of the sperm cell fuses with the nucleus of the egg cell to form a single nucleus. This fusion results in the formation of a fertilised egg called a zygote.

LONG ANSWER QUESTIONS

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

Answer: Fish show external fertilisation because the female releases eggs and the male releases sperms into water outside the body. The fusion of gametes happens in water, not inside the female body.

25. 

   

After observing Fig. 9.3 answer the following.
(a) Read the following statements and label them in the figure:
(i) The part which produces female gametes.
(ii) The part where development of the baby takes place.
(iii) The part through which the developing embryo passes to reach the uterus.
(b) Explain the future development of the embryo that would take place after it gets embedded in the uterus.

Answer:  (a) (i) Ovary     (ii) Uterus    (iii) Oviduct

(b) After embedding in the uterus, the embryo continues to grow and forms different body parts. When all body parts become identifiable, it is called a foetus. Further development takes place in the uterus until birth.

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

Answer: Hens show internal fertilisation, where sperm fuses with egg inside the female body, and eggs are laid later with hard shells. Frogs show external fertilisation, where eggs and sperms are released in water and fuse outside the body. Both are oviparous as they lay eggs, but fertilisation method is different.

27. Observe the following figures.

  

   

(i) Identify the stages a to d in Fig. 9.4 during development of human baby.
(ii) Arrange the stages in correct sequence of development.
(iii) Explain the development that takes place in any one stage.

Answer:  (i) (a) Implantation  (b) Fertilization  (c) Embryo   (d) Zygote

(ii)  (b) Fertilization → (d) Zygote → (c) Embryo → (a) Implantation 

(iii) In fertilisation, a sperm fuses with an egg to form a zygote. This zygote is the first cell of a new individual and later divides repeatedly to form an embryo.