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Reproduction In Animals

Class 8th Science CBSE Solution
Exercises
  1. Explain the importance of reproduction in organisms.
  2. Describe the process of fertilization in human beings.
  3. Internal fertilization occurs (i) in female body. (ii) outside female body. (iii) in male…
  4. A tadpole develops into an adult frog by the process of (i) fertilization (ii)…
  5. The number of nuclei present in a zygote is (i) none (ii) one (iii) two (iv) four Choose…
  6. Indicate whether the following statements are True (T) or False (F). (a) Oviparous animals…
  7. Give two differences between a zygote and a foetus.
  8. Define asexual reproduction. Describe two methods of asexual reproduction in animals.…
  9. In which female reproductive organ does the embryo get embedded?
  10. What is metamorphosis? Give examples.
  11. Differentiate between internal fertilization and external fertilization.…
  12. Complete the crossword puzzle using the hints given below. Across 1. The process of the…
Exercises
Question 1.

Explain the importance of reproduction in organisms.
Answer:

Reproduction is very important for the organisms :-

(1) The organisms reproduce to carry on their generation of young ones like them. Reproduction helps to sustain their genes on the planet if reproduction do not take place, no living being will survive on the earth.

(2) The genes of an organism are carried over to its next generation through reproduction means only
Question 2.

Describe the process of fertilization in human beings.
Answer:

Fertilization is defined as the fusion of male gamete with female gamete resulting in the formation of zygote. In case of Human Beings process of Fertilization is defined as the fusion of sperm cell from the male with the egg cell from the female resulting in the formation of fertilized egg cell called zygote. The sperm cell is released by Penis whereas the egg cell are made by Ovaries.







Question 3.

Choose the most appropriate answer.

Internal fertilization occurs

(i) in female body.

(ii) outside female body.

(iii) in male body.

(iv) outside male body.
Answer:

Option (i) is correct i.e. in female body.

Internal fertilization is that which take splace inside the body of an organism.
Question 4.

Choose the most appropriate answer.

A tadpole develops into an adult frog by the process of

(i) fertilization

(ii) metamorphosis

(iii) embedding

(iv) budding
Answer:

Option (ii) is correct i.e. metamorphosis

The transformation of a larvae into adult is called metamorphosis.
Question 5.

Choose the most appropriate answer.

The number of nuclei present in a zygote is

(i) none

(ii) one

(iii) two

(iv) four
Answer:

Option (ii) is correct i.e one

Inside a zygote, only one nucleus is present.
Question 6.

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 frogs. ( )

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

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

(f) Amoeba reproduces by budding. ( )

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

(h) Binary fission is 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. ( )
Answer:

(a) False

(b) True


(c) True


(d) False


(e) True


(f) False


(g) False


(h) True


(i) True


(j) False
Question 7.

Give two differences between a zygote and a foetus.
Answer:
Question 8.

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

Asexual reproduction is a mode of reproduction in which only one parent is involved to reproduce offspring. In asexual reproduction, the off springs produced are exact copies of their parents. It is generally observed in very small sized organisms. Binary fission, Budding, Fragmentation etc. are the examples of asexual reproduction.

1) Budding: This type of reproduction takes place in Hydra and Bacteria. A part of the organism starts budding out. Slowly it grows and develops into a separate individual. See image below:



2) Binary fission – In this type of reproduction, a single organism gets divided into two. This type of reproduction takes place in Amoeba. The nucleus of the Amoeba gets divided into two followed by division of their bodies, each part getting one nucleus and developing into a separate individual. See image below:
Question 9.

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

The embryo gets embedded in the wall of the uterus.
Question 10.

What is metamorphosis? Give examples.
Answer:

The transformation of the larva into an adult is called metamorphosis. Metamorphosis is a biological process which involves sudden and abrupt changes in the body structure of the animal by cell growth and differentiation. It is generally observed in amphibians and insects.

Examples: frogs and butterflies.
Question 11.

Differentiate between internal fertilization and external fertilization.
Answer:




Question 12.

Complete the crossword puzzle using the hints given below.
Across
1. The process of the fusion of the gametes.
6. The type of fertilization in the 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 the fertilized egg.
4. These animals lay eggs.
5. A type of fission in amoeba.
Answer:

Across

1. The process of the fusion of the gametes: Fertilization

6. The type of fertilization in the hen: Internal fertilization

7. The term used for bulges observed on the sides of the 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 the fertilized egg: Zygote

4. These animals lay eggs: Oviparous

5. A type of fission in amoeba: Binary