NCERT Solutions for Class 8 Science Chapter 9 : Reproduction in Animals

Q:

In which female reproductive organ does the embryo get embedded?

A:

The embryo gets embedded in the walls of uterus. In the uterus, the embryo grows and develops all the body parts.

Q:

Define asexual reproduction. Describe two methods of asexual reproduction in animals.

A:

Asexual reproduction is a type of reproduction in which only one parent is involved and the offspring is genetically identical to the parent cell.

Two methods of asexual reproduction are budding and binary fission.

  1. Budding: In this type of asexual reproduction, an outgrowth appears on the parent’s body. This outgrowth is termed as bud. The bud gradually grows into a small individual and then detaches itself from the parent’s body. It continues to grow and live as a new individual in the environment. Eg; Hydra.
  2. Binary fission: In this type of asexual reproduction, the nucleus of the parent’s body divides into two nuclei. After that the body divides into two and each body part receives a nucleus. Eg; Amoeba.

Q:

What is metamorphosis? Give examples.

A:

Metamorphosis is a biological process of transformation of an immature form, such as larva, into an adult through drastic changes. It is observed in frogs (transformation of tadpole into adult frog) and in insects (transformation of larva into moths or butterflies).

Q:

Give two differences between a zygote and a foetus.

A:

Differences between a zygote and a foetus are:

Zygote

Foetus

It is unicellular. Hence, no well-defined body parts.

It is multicellular and has well-defined body parts.

It forms due to the fertilisation of sperm and ovum.

It forms after the process of fertilisation in which zygote multiplies and grows into a multicellular body.

Q:

Describe the process of fertilisation in human beings.

A:

Fusion of a sperm and an ovum is called fertilisation. In human beings, the process of fertilisation takes place in the oviducts. The sperms produced by testes in male’s body are transferred into the female body. In female’s body, one matured ovum is released into the oviduct by one of the ovaries every month. In the oviduct, the sperm comes in contact with the ovum and fuses with it. During the process of fusion, the nuclei of the sperm and the ovum fuse to form one single nucleus. This results in the formation of zygote.

Q:

Complete the crossword puzzle using the hints given below.
Across
1. The process of the fusion of the gametes.
6. The type of fertilisation in hen.
7. The term used for bulges observed on the sides of the body of hydra.
8. Eggs are produced here.

Down
2. Sperms are produced in these male reproductive organs.
3. Another term for in vitro fertilisation.
4. These animals lay eggs.
5. A type of fission in amoeba.

A:

Q:

Differentiate between internal fertlisation and external fertlisation.

A:

Characters

Internal Fertilisation

External Fertilisation

Site of fertilisation

Inside female body

Outside female body

Number of eggs/offspring produced

Less

Large

Chances of survival of eggs/offspring

High

Low

Example

Mostly mammals

Generally fish and frog

Q:

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.

(b) A tadpole develops into an adult frog by the process of
(i) fertilisation
(ii) metamorphosis
(iii) embedding
(iv) budding

(c) The number of nuclei present in a zygote is
(i) none
(ii) one
(iii) two
(iv) four

A:

(a) (i) in female body.

(b) (ii) metamorphosis

(c) (ii) one

Q:

Explain the importance of reproduction in organisms.

A:

Importance of reproduction in organisms is:

  1. Reproduction ensures the continuity of a species.
  2. It also maintains the number of individuals in a population.
  3. It is also responsible for variations in organisms in a population that help them to survive in the environment.

Q:

Indicate whether the following statements are True (T) or False (F).
(a) Oviparous animals give birth to young ones. ( )
(b) Each sperm is a single cell. ( )
(c) External fertilisation takes place in frog. ( )
(d) A new human individual develops from a cell called gamete. ( )
(e) Egg laid after fertilisation is made up of a single cell. ( )
(f) Amoeba reproduces by budding. ( )
(g) Fertilisation is necessary even in asexual reproduction. ( )
(h) Binary fission is a method of asexual reproduction. ( )
(i) A zygote is formed as a result of fertilisation. ( )
(j) An embryo is made up of a single cell. ( )

A:

(a) Oviparous animals give birth to young ones. (F)
(b) Each sperm is a single cell. (T)
(c) External fertilisation takes place in frog. (T)
(d) A new human individual develops from a cell called gamete. (F)
(e) Egg laid after fertilisation is made up of a single cell. (T)
(f) Amoeba reproduces by budding. (F)
(g) Fertilisation is necessary even in asexual reproduction. (F)
(h) Binary fission is a method of asexual reproduction. (T)
(i) A zygote is formed as a result of fertilisation. (T)
(j) An embryo is made up of a single cell. (F)

Start Your
7-Days Free Trial
and experience it yourself
Start Trial
Play StoreApp Store
Flying Girl
A subscription
that’s worth your
money
Get the best classroom experience on
India’s leading learning platform

Get
in touch

Have a query about our services?
Get in touch with us and we will
guide you through a new world of
redefined learning

Union
Get OTP
Submit