Reproduction in Animals (NCERT Solutions, Class 8)

(1) Explain the importance of reproduction in organisms.

Ans– Reproduction in the organisms is very necessary because only by this method population of living being will increase.

(2) Describe the process of fertilisation in human beings.

Ans- The process in which nuclei of egg from the female and the nuclei of sperm from the male fused to form a fertilized egg or zygote is called fertilization.

(3) Choose the most appropriate answer.

(a) Internal fertilization occurs

(i) in female body.

(ii) outside female body.

(iii) in male body

(iv) out side male body.

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

(i) fertilisation (ii) metatmorphosis (iii) embedding (iv) budding

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

(i) none (ii) one (iii) two (iv) four

Ans-

(a) Internal fertilisation occurs

(i) in female body.

(ii) outside female body.

(iii) in male body

(iv) out side male body.

Ans- Internal fertilization occurs in female body

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

(i) fertilisation (ii) metamorphosis (iii) embedding (iv) budding

A tadpole develops into an adult frog by the process of metamorphosis.

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

(i) none (ii) one (iii) two (iv) four

The number of nuclei present in a zygote is one.

(4) 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 fertilization 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 id a method of asexual reproduction.

(i) A zygote is formed as a result of fertilization.

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

Ans-

(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. T

(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 fertilization. T

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

(5) Give two differences between a zygote and a foteus.

Ans- Differences between a zygote and foetus are tabulated below:-

SN	Zygote	Foetus
1.	It is a fertilised egg.	It is a stage where all the body part of the embryo can be identified.
2.	It is further develops in to embryo.	It is a develop stage of embryo.

(6) Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Ans- When process of reproduction is completed by a single parent is called asexual reproduction.

Types of asexual reproduction

(i)The new individual is born or develops from the buds, it is called budding.

Eg:- Hydra

Bulges of hydra are known as buds. Parent hydra develops a bump which grows and separate from the parent hydra as independent hydra.

(ii) When a microscopic organism divides its nucleus in two parts, each part has its own nuclei, is known as binary fission.

Eg:- Amoeba

Amoeba begins the process of reproduction by the division of its nucleus into two nuclei. The body of parent amoeba is divided into two parts with nucleus in each part. The body parts separates from the parent amoeba are known as daughter amoebae.

(7) In which female reproductive organ does the embryo get embedded?

Ans- Uterus is the female reproductive organ does the embryo get embedded.

(8) What is metamorphosis? Give examples.

Ans- Metamorphosis is a process in which structure of animals change drastically after their birth.

Eg:- Frog, silk worm etc.

The young ones develop in to adults. The young ones of viviparous animals look like their parents. But in some oviparous animals young ones looks different from their patterns.

(9) Differentiate between internal fertilisation and external fertilisation.

Ans- Difference between internal fertilisation and external fertilisation are tabulated below:-

SN	Internal Fertilisation	External Fertilisation
1.	It takes place inside the female body.	It takes place out side the female body.
2.	It takes place in viviparous animals.	It takes place in oviparous animals.
3.	Eg:- Human, cow, hen etc.	Eg:- Frog and aquatic animals