NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animal

Students will learn how reproduction is important to maintain the continuity of life on Earth. They will learn about the modes of reproduction like sexual and asexual reproduction. They will learn how males and females differ and how genetic material is transferred from parent to child.

The chapter explains in detail the connection between a zygote, an embryo and a foetus. Students will also learn the different methods of asexual reproduction in organisms like bacteria, hydra and amoeba. In detail chapter 10

Download PDF of NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animal

Question 1: Explain the importance of reproduction in organisms.

Answer: Reproduction is the means to continue life. Organisms reproduce to produce more members of their kind to maintain their number. If an organism does not reproduces then he or she will be the last one of their kind and their species would become extinct. Even an organism as small as a bacteria also reproduces so that their number is maintained in the environment. Reproduction helps to bring new members of a species into the ecosystem

Question 2: Describe the process of fertilisation in human beings.

Answer: Human beings undergo sexual reproduction to produce offspring. The male reproductive cell or sperm is released from male reproductive organ and the female reproductive cell called egg is produced from female reproductive organ. These two cells come together and fuse to form a zygote in a process called fertilisation. This zygote is like a plant seed, which develops into a complete organism. fertilisation occurs inside female body and zygote is formed inside uterus. In uterus the zygote develops into a a child that we call ‘foetus’.

Question 3: Choose the most appropriate answer.

(a) Internal fertilisation occurs

(i) in female body

(ii) outside female body

(iii) in male body

(iv) outside male body

Correct answer: (i) in female body.

Internal fertilisation means the fertilisation that is occurring inside the body of an organism. The females contain uterus where the baby develops so the fertilisation takes place inside female body.

In frog the fertilisation takes place outside the female body.

Fertilisation never takes place inside male body.

(b) A tadpole develops into an adult frog by the process of

(i) fertilisation

(ii) metamorphosis

(iii) embedding

(iv) budding

Correct answer: (ii) metamorphosis.

The development of tadpole into adult frog is termed as metamorphosis as there is a significant change in the shape, appearance and size of the animal.

Fertilisation is the process where sperm meets egg cell to form zygote.

Embedding is the process where zygote attaches to uterus and then grows into a foetus.

Budding is a type of asexual reproduction shown by yeasts.

(c) The number of nuclei present in a zygote is

(i) none

(ii) one

(iii) two

(iv) four

Correct answer: (iii)

The zygote is formed when sperm cell containing one nucleus meets with egg cell containing one nucleus. These two cells fuse and their nuclei are then present inside the zygote. So a zygote has two nuclei from each cell.

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Question 4: Indicate whether the following statements are True (T) or False(F).

(a) Oviparous animals give birth to young ones.

Correct answer: F

Viviparous animals give birth to young ones and oviparous animals lay eggs.

(b) Each sperm is a single cell.

Correct answer: T

Sperm is a male reproductive cell and it is produced inside the testis of males. The sperms are single cells with nucleus that fuse with female egg cell.

(c) External fertilisation takes place in frog.

Correct answer: T

External fertilisation occurs when the egg cell fuses with sperm cell outside the female body, that is in the surrounding. The frog eggs are fertilised in water.

(d) A new human individual develops from a cell called gamete.

Correct answer: F

Gametes are the reproductive cells released from male and female reproductive organs. These gametes form zygote which forms human individual. So individual develops from zygote.

(e) Egg laid after fertilisation is made up of a single cell.

Correct answer: T

The egg that is laid after fertilisation is the zygote which develops into embryo. This embryo contains one cell with two nuclei.

(f) Amoeba reproduces by budding

Correct answer: F

Amoeba reproduces by the process of binary fission and not budding.

(g) Fertilisation is necessary even in asexual reproduction.

Correct answer: F

Asexual reproduction does not involve the need of fertilisation as no gametes are produced inside parent organisms.

(h) Binary fission is a method of asexual reproduction

Correct answer: T

Methods like binary fission, budding are means of asexual reproduction as in this no gametes or fertilisation is required for producing new organisms.

(i) A zygote is formed as a result of fertilisation

Correct answer: T

A zygote is formed from the fusion of sperm and egg cell which contains one cell but two nuclei. This fusion is called fertilisation.

(j) An embryo is made up of a single cell.

Correct answer: T

The embryo contains a single cell but it has two nuclei. The single cell is formed from meeting of male and female gamete. This embryo grows to form a baby.

Question 5: Give two differences between a zygote and a foetus.

Zygote	Foetus
Zygote is the stage immediately after fusion of male and female gamete.	Foetus is the stage where the embryo forms all the body structures like hands, legs, body and so on.
Zygote is the start point of forming an individual.	Foetus is the end point of forming an individual after which it is brought outside the uterus.

Question 6: Define asexual reproduction. Describe two methods of asexual reproduction.

Asexual reproduction is the method of forming new individuals or organisms without the involvement of fertilization. The parent organism forms a new organism without producing male and female gamete.

The two modes of asexual reproduction are as follows:

Budding: In budding the organisms like yeast develops a small bud that tears off from the organism and gradually grows into complete yeast organism.

Binary fission: In binary fission the organisms divides into two and these two parts form complete organisms.

Question 7: In which female reproductive organ does the embryo get embedded?

The female reproductive system contains ovaries, fallopian tubes and uterus. The embryo gets embedded in the wall of the uterus and develops into foetus.

Question 8: What is metamorphosis? Give examples.

Metamorphosis is the mechanism by which larva of an organism develops into adult form and undergoes major changes in size, shape and appearance.

For example, in frogs the young one of a frog is called tadpole which looks very different from adult frog. It then undergoes changes and forms adult frog. This entire process is metamorphosis.

Question 9: Differentiate between internal and external fertilization.

Internal fertilization	External fertilization
The fertilization that takes place inside the body of female organism is called internal fertilization.	The fertilization that takes place outside the body of female is called external fertilization.
Example: fertilization in humans	Example: fertilization in frog.

Question 10: Complete the crossword puzzle using the hints given below.

ACROSS

1. The process of fusion of the gametes- Fertilization

6. The type of fertilization in hen- Internal

7. The term used for bulges observed on the sides of body of hydra-Buds

8. Eggs are produced here-Ovary

DOWN

2. Sperms are produced in these male reproductive organs-Testis

3. Another term for in vitro fertilization- IVF

4. These animals lay eggs-Oviparous

5. A type of fission in amoeba- Binary

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