NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animals

Q1. Explain the importance of reproduction in organisms.

Answer:

Reproduction in organisms is important to maintain the continuity of organisms and to carry on their generation to the next generation. If reproduction does not take place, no living being will survive on the earth. Because, of this process, plants, animals, humans even all the living organisms are still alive, if reproduction has not been there then all the plants and animals would have become extinct.

Q2. Describe the process of fertilisation in human beings.

Answer:

The process of fertilisation is the meeting of an egg cell from the female and a sperm cell from the male. Basically the fusion of a sperm and an ovum. When sperms come in contact with an egg, one of the sperms may fuse with the egg. Such fusion of the egg and the sperm is called fertilisation.

Fertilisation which takes place inside the female body is called internal fertilisation.

Q3. 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

Answer:

(i) In female body

Q3. Choose the most appropriate answer.

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

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

Answer:

(ii) metamorphosis In the case of tadpoles, they transform into adults capable of jumping and swimming. The transformation of the larva into an adult through drastic changes is called metamorphosis

Q3. Choose the most appropriate answer

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

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

Answer:

(ii) One

Q4. Indicate whether the following statements are True (T) or False (F).

(a) Oviparous animals give birth to young ones. ( )

Answer:

(False) oviparous organisms lay eggs.

Q4. Indicate whether the following statements are True (T) or False (F).

(b) Each sperm is a single cell. ( )

Answer:

(True) Gametes are single-celled.

Q4. Indicate whether the following statements are True (T) or False (F)

(c) External fertilization takes place in frog. ( )

Answer:

(True) External fertilization is common in aquatic animals.

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

Q4. Indicate whether the following statements are True (T) or False (F).

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

Answer:

( False ) gametes fuse together to form a zygote and give rise to a new human being.

Q4. Indicate whether the following statements are True (T) or False (F).

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

Answer:

( True ) the fertilised egg is a single cell.

Q4. Indicate whether the following statements are True (T) or False (F).

(f) Amoeba reproduces by budding. ( )

Answer:

( False ) amoeba reproduces by binary fission. (budding happens in hydra)

Solutions of NCERT for Class 8 science Chapter 9 Reproduction in Animals :

Q4. Indicate whether the following statements are True (T) or False (F).

(g) Fertilisation is necessary even in asexual reproduction. ( )

Answer:

( False ) In asexual reproduction, only one parent is required so the fusion of gametes does not take place.

Q4. Indicate whether the following statements are True (T) or False (F)

(h) Binary fission is a method of asexual reproduction. ( )

Answer:

( True ) In binary fission, only single organism is required to produce two individuals. So it is a method of asexual reproduction

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

Q4. Indicate whether the following statements are True (T) or False (F).

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

Answer:

( True ) In fertilisation, one gamete of male and one gamete female fuse together to form a zygote.

Q4. Indicate whether the following statements are True (T) or False (F). (j) An embryo is made up of a single cell. ( )

Answer:

(False) it is a multicellular because it is formed from zygote after repeated division.

Q5. Give two differences between a zygote and a foetus.

Answer:

Zygote-

• The zygote formed after the fertilisation of male sperm and female ovum.
• The zygote divides repeatedly to give rise to a ball of cells. The cells then begin to form groups that develop into different tissues and organs of the body. This developing structure is termed an embryo.

Foetus-

• The stage of the embryo in which all the body parts can be identified is called a foetus.
• Embryo gradually develops into a foetus.

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

Q6. Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Answer:

In this type of reproduction, there is no need for the fusion of male and female gametes. It is a mode of reproduction in which only a single parent is involved is called asexual reproduction

Two methods of asexual reproduction in animals-

(i) Binary fission - In this type of asexual reproduction, a single cell organism is divided into two halves. Amoeba can reproduce by this method. It begins the process of reproduction by the division of its nucleus into two nuclei. This is followed by the division of its body into two, each part receiving a nucleus. Finally, two amoebae are produced from one parent amoeba

(ii) Budding - In this method developing of new individuals is by the bulges and they are called buds formed on the parent body.

These type of asexual reproduction is common in Hydra. In hydra, the new individuals develop as outgrowths (called buds) from a single parent. While being attached to the parent, develops into smaller individuals and when these get matured, they detach from the parent and become individual ones.

Q7. In which female reproductive organ does the embryo get embedded?

Answer:

The embryo gets embedded in the wall of the uterus for further development. The embryo continues to develop in the uterus. It gradually develops bodyparts 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.

Q8. What is metamorphosis? Give examples.

Answer:

Metamorphosis - The biological transformation of the larva into an adult through drastic changes is called metamorphosis.

Example- life cycle of a toad.

Q9. Differentiate between internal fertilisation and external fertilisation.

Answer:

Internal fertilisation-

• Fertilisation which takes place inside the female body is called internal fertilisation
• survival chances of the offspring are more
• animals including humans, cows, dogs and hens

External fertilisation-

• fertilisation in which the fusion of a male and a female gamete takes place outside the body of the female is called external fertilisation.
• chances of survival of offspring are less
• It is very common in aquatic animals such as fish, starfish, etc.

NCERT solutions for class 8 science chapter 9 reproduction in animals :

Q10. 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.

Answer:

1. FERTILISATION
2. TESTIS
3. ZYGOTE
4. OVIPAROUS
5. BINARY
6. INTERNAL
7. BUDS
8. OVARY