Science class 8 chapter 9 – Reproduction in Animals – NCERT exercise solutions

Science class 8 chapter 9 – Reproduction in Animals – NCERT exercise solutions ( Question-Answer)

Q.1 Explain the importance of reproduction in organisms.

Answer – Reproduction is the most important action or process as it ensures the continuation of similar kinds of individuals, generation after generation.

All the living organisms reproduce to produce young ones like themselves.

If there were no reproduction takes place then all living beings can extinct and non-living beings will survive on the earth.

So, reproduction is important for the survival of all living beings.

Q.2 Describe the process of fertilization in human beings.

Answer – The fusion of (male gamete) sperm with (female gamete) ovum, this process is known as fertilization.

Fertilization occurs in the female body in the fallopian tube.

Process – First of all, millions of sperm released by the male body during mating. But, only one sperm can fuse with an egg when the sperm comes in contact with the egg.

The result of this union is the production of a zygote cell or fertilized egg. We all know that zygote is the beginning of a new individual.

The result of fertilization is the formation of a zygote which begins to develop into an embryo.

So, the process of fertilization is the meeting of an egg cell from the mother and a sperm cell from father, so the new individual inherits some characteristics from the mother and some from father.

Q.3 Choose the most appropriate answer.

(a) Internal fertilization occurs

(i) in female body.

(ii) outside female body.

(iii) in male body.

(iv) outside male body.

Answer -(i) in female body.

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

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

Answer – (ii) metamorphosis

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

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

Answer – (iii) two

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

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

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

(c) External fertilization takes place in a frog.  ( T )✔

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

(e) Egg laid after fertilization is made up of a single cell.  ( F )❌

(f) Amoeba reproduces by budding. ( F)❌

(g) Fertilization is necessary even in asexual reproduction. ( T )✔

(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 )❌

Q.5 Give two differences between a zygote and a foetus.

Answer – There are two differences between zygote and foetus-

        Zygote Foetus
1. Unicellular structure

 

2. A zygote is the result of fertilization
  1.  Multicellular structure

 


2. The stage of the embryo which resembles a human being is called a foetus.

Q.6 Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Answer – Asexual reproduction is that type of reproduction in which a single parent is involved. In this, the fusion of gametes doesn’t involve.

The two methods of asexual reproduction are as follows-

(i) Budding

(ii) Binary Fission

Budding-

It is a type of asexual reproduction. The new organism develops from a bud.

Ex. In hydra, a new individual develops from the bud and this type of asexual reproduction is known as budding.

In this, a bud develops on the body of a multicellular organism and starts resembling its mother’s body. Finally, buds get detached from the mother’s body and begin a new life as a new individual.

Binary Fission- Binary fission is a type of asexual reproduction and takes place in a unicellular organism.

Let us take an example- Amoeba.

The first cell of amoeba divides into two daughter cells. Each of the daughter cells becomes a new individual and begin a new life.

Q.7 In which female reproductive organ does the embryo get embedded?

Answer – Uterus is the female reproductive organ where the embryo gets embedded.

Q.8 What is metamorphosis? Give examples.

Answer – Transformation of the larva into an adult through drastic changes is called metamorphosis.

Eg. The Larva of butterfly undergoes metamorphosis to become a butterfly.

Tadpole undergoes metamorphosis to become a frog.

Q.9 Differentiate between internal fertilisation and external fertilisation.

Answer

 Internal FertilisationExternal fertilization
 1. It takes inside the female body.

 

2. It is observed in humans, reptiles and some other animals.

3. There is no need to lay a large number of eggs.

 1. It takes outside the female body.

 

2. It is observed in frog, fish, starfish, aquatic animals.

3. There is a large number of eggs need to be laid.

Q.10 Complete the crossword puzzle using the hints given below.

Across

1. The process of fusion of the gametes

6. The type of fertilization in a hen

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

8. Eggs are produced here.

Down

2. Sperm are produced in these male reproductive organs.

3. Another term for in vitro fertilization.

4. These animals lay eggs.

5. A type of fission in amoeba.

Science class 8 chapter 9- Reproduction in Animals – NCERT exercise questions answers ended ✌✌✌✌

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