NCERT Solution of class 8 // Science // Chapter 9. Reproduction in animals

 NCERT Solution > Class 8  > Science

Chapter 9 .   Reproduction in animals.



Question 1.  Explain the importance of reproduction in organism? 

Answer - Reproduction process shows following benefits- 

1. It maintain the continuity of life so that they become safe from life.

2. Dead organism due to disease ,aging ,growth are replaced by new organism

3. Due to different combination variation takes place in the organism and new characters are produced.

4. Variation and features are transferred from one generation to the next generation.

5. To maintain the existence of organism

6. It increases the number of cells  and organisms.

7. Replication of DNA takes place and hereditary characters are transferred from one generation to the next generation.

Question. 2. 

Describe the process of fertilization in human beings?

Answer- 1. In human being the fertilization process is internal it takes place inside the female body.

2. Fertilization means Union of male gamete with female gamete.

3. Fertilization in human occurs within the fallopian tube of female.

4. When sperm come in contact with an egg one of the sperm make fuse with the egg .

5. Such fusion of sperm and egg is called fertilization

6. Male gamete nucleus and female gamete nucleus combined to each other and form a zygote 

7. In this type of fertilization male gamete  combined with female gamete that's why the individual carry characters of both mother and father.

Question 3

Choose the most appropriate answer

a)  Internal fertilization occur

Answer- In female body

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

Answer- Metamorphosis

c) The number of nuclei present in zygote

Answer - Two 

Question 4

Indicate whether the following statement are true or false

a) Oviparous animals give birth to young ones- false

b) Each sperm is single cell- true

c) External fertilization takes place in frog- true

d) New human individual develops from cell called gamete- true

e) Egg laid after fertilization is made up of single cell - false 

f) Amoeba reproduce by budding- false

g) Fertilization is necessary even in asexual reproduction- false

h) Binary fision is a method of asexual Reproduction - true

i) Zygote is formed as a result of fertilization- true

j) An embryo is made up of single cell- false

Question 5 

 Give two difference between a zygote and  a foetus? 

Answer-

Zygote -. 

1. Zygote is made up of combination of Male nucleus with female nucleus 

2. Zygote did not show the body organ

Foetus- 

1.  foetus is developed from the embryo

2. In foetus  all body parts can be identified.

Question 6

 Define Asexual Reproduction describe two methods of asexual reproduction in animals? 

Ans- Definition- 

sexual reproduction is a type of reproduction in which only single parent is involved.

 the methods of asexual reproduction in animal are as follow- 

1. Budding-

It is one of the type of  asexual reproduction found  in lower organisms.  example -hydra

a) The body of hydra shows one or more bulges.

b) These bulges are developing new individual and they are called Buds.

c) After acquiring the proper growth these  Bud detached from the parent body and grow separately.

2. Binary fission-

This type of the reproduction also found in the lower organisms. 

example - amoeba

a) Amoeba is a single cell organism.

b)  firstly the nucleus of the Amoeba is divided into two .

c) and then the cytoplasm of the cell body is divided into two and each part receiving A nucleus .

Question 7

In which female reproductive organ does  embryo get embedded? 

Answer- 

In human female. 

Question 8

What is metamorphosis?  Give examples

Answer - "The transformation of Larva into an adult through drastic changes is called metamorphosis". 

Example- frog , silkworm etc. 

Question 9

 Differentiate between Internal fertilization and external fertilization? 

Answer- 

Internal fertilization-

1. Internal fertilization takes place inside the body of female.

2. In internal fertilization the embryo get embedded in female reproductive organ.

3. Example- Humans ,cows ,dogs ,and hens

External fertilization 

1. External fertilization takes place outside the female body

2. Generally this type of fertilization takes place in water

3. Examples- It is very common in aquatic animals such as fish ,starfish etc.

Question 10

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 hen

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

8. Eggs are produced here

Down

2. Sperm produced in these Male reproductive organs

3. Another term for in vitro fertilization

4. The animals lay eggs

5.  A type of Fission in amoeba






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