NCERT Class 8 Science Chapter 6 ‘Reproduction in Animals’: Notes and Solutions (Free PDF)

When the exam season is upon us, only then do we understand the importance of well-written notes. They can provide a way to go through the chapter easily and understand the key concepts. Also, they can help us revise the chapter with the utmost ease without missing out on any concepts. We have created NCERT Solutions and Notes for Class 8 Science Chapter 6: Reproduction in Animals to assist you during the exam. After the notes, you will also find Solutions to the NCERT exercises and a downloadable PDF of the same.

Download the NCERT Class 8 Science Chapter 6 Solutions PDF Here!

Explore all the Chapters of Class 8 Science:

Chapter 1	Chapter 2	Chapter 3
Chapter 4	Chapter 5	Chapter 6
Chapter 7	Chapter 8	Chapter 9
Chapter 10	Chapter 11	Chapter 12
Chapter 13

Class 8 Science Chapter 6 Reproduction in Animals: Introduction

Reproduction is a process that is essential for the continuation of a species. It ensures the continuation of similar kinds of individuals, generation after generation. There are basically two modes of reproduction:-

• Sexual reproduction
• Asexual reproduction

Also Read: Animal Biotechnology – Career in Bioscience

Class 8 Science Chapter 6 Reproduction in Animals: Sexual Reproduction Notes

In this section of Class 8 Science Chapter 6 notes, we will explore all aspects of sexual reproduction. 

Sexual Reproduction

The mode of reproduction that involves the fusion of male and female gamete to form a zygote is known as sexual reproduction. 

In this type of reproduction, both males and females have different reproductive parts.

Male Reproductive Organs

The organs included in the male reproductive parts are:-

• A pair of testes (singular, testis)
• Two sperm ducts
•  A penis

Sperms or the male gametes are produced by the testes in millions.

Parts of a sperm include:-

• A Head
• A middle piece
• A Tail

Each sperm is a single cell with all the usual cell components.

Female Reproductive Organs

The organs in a female reproductive parts include:

• A pair of ovaries
• Oviducts (fallopian tubes)
• The uterus

The ova (egg) or the female gamete is produced by the ovaries which is also single-celled.

Every month, a single matured egg is released in the oviducts by the ovaries. The uterus is the part where the development of the baby takes place.

Fertilisation

The process of fusion of the male gamete with the female gamete to form a zygote is known as fertilisation.

• Since the gametes from both the individuals, the mother and the father, fuse to form the zygote, the new individual hence, inherits characters from both of them. 

Now, based on the location of fertilisation, it can be of two types:

Internal fertilisation	External fertilisation
When fertilisation takes place inside the body of the female, it is known as internal fertilisation.	When fertilisation takes place outside the body of the female, it is known as external fertilisation.
In this fertilisation, the young ones formed are more protected.	In this fertilisation, the young ones formed are comparatively less protected.
The number of female gametes released is low.	The number of female gametes released is more.
Example:- humans, cows, dogs and hens.	Example:- frog, fish, starfish, etc.

During the rainy season, frogs and toads move to the ponds, where the female lays eggs in large numbers. The male deposits sperm over them. Each sperm swims randomly in water with the help of its long tail. The sperm comes in contact with the eggs. This results in fertilisation. 

External fertilisation is more common in aquatic animals.

IVF (In-Vitro Fertilisation)

Let us understand the IVF process

• When a mother’s oviducts are blocked and she is unable to bear a baby, then the egg is collected from the mother and sperm are collected from the father, and are made to fuse in a test tube. 
• The zygote thus formed is allowed to develop for about a week and then placed in the mother’s uterus where it grows and is delivered like any other baby.
• Babies born in such a way are known as test-tube babies which is a misnomer as the babies don’t actually grow in test tubes.

Development of Embryo

After the zygote is formed, it undergoes division to form a ball of cells. These cells start to form groups and differentiate to give rise to different tissues and organs. This developing structure is known as the embryo.

Now, let us understand the process of embryo development:

• The embryo gets embedded in the wall of the uterus and continues to develop.
• Gradually, the embryo develops all the body parts such as hands, legs, eyes, ears, etc.
• When the embryo develops body parts, it is known as a foetus.
• After the complete development of the foetus, the baby is delivered by the mother. 
• In the case of hens, as the zygote divides and travels down the oviduct, many protective layers are added around the shell is also one such protective layer. After the egg is delivered, it takes about three weeks for the embryo to develop into a chick when sufficient warmth is given.
• In external fertilisation, the development of the embryo takes place outside the female body. The embryos continue to grow within their egg coverings. After the embryos develop, the eggs hatch.

Viviparous and Oviparous Animals

Now, let us learn the definition of viviparous and oviparous animals:

• The animals that give birth to young ones are called viviparous animals. 
• The animals that lay eggs are called oviparous animals.

Also Read: 100 Branches of Biology from A to Z

Class 8 Science Chapter 6 Reproduction in Animals: Asexual Reproduction Notes

In this part of the Class 8 Science Chapter 6 notes, we will learn about asexual reproduction and associated concepts. 

• Microorganisms like hydra and amoeba, reproduce by asexual mode of reproduction. 
• The mode of reproduction in which only a single parent is involved is known as asexual reproduction. 
• In hydra, a bulge starts appearing on its body which is known as a bud that develops into a new individual and eventually separates from the parent. This is known as budding in hydra.

• Amoeba reproduces by binary fission. In this, the nucleus of the amoeba divides at first, then the body divides into two parts forming two amoeba from one amoeba.
• The type of asexual reproduction, where an organism reproduces by dividing into two new individuals is known as binary fission. 

Cloning

Cloning is the production of an exact copy of a cell, any other living part, or a complete organism.

Here are some key pieces of information about cloning: 

• Cloning of an animal was successfully performed for the first time by Ian Wilmut and his colleagues at the Roslin Institute in Edinburgh, Scotland.
• They successfully cloned a sheep named Dolly. Dolly was born on 5th July 1996 and was the first mammal to be cloned.
• For cloning Dolly, a cell was collected from the mammary gland of a female Finn Dorsett sheep. An egg was obtained from a Scottish blackface ewe. The nucleus was removed from the egg. Then, the nucleus of the mammary gland cell from the Finn Dorsett sheep was inserted into the egg of the Scottish blackface ewe whose nucleus had been removed.
• The egg thus produced was implanted into the Scottish blackface ewe. Development of this egg followed normally and finally, Dolly was born.
•  It was found to be absolutely identical to the Finn Dorsett sheep from which the nucleus was taken. Dolly did not show any character of the Scottish blackface ewe.

Also Read: Courses in Biology after 12th Except MBBS

Important Definitions in NCERT Class 8 Science Chapter 6: Reproduction in Animals

Some important definitions from the Class 8 Science Chapter 6 ‘Reproduction in Animals’ are mentioned below:

• Sexual reproduction: The mode of reproduction that involves the fusion of male and female gamete to form a zygote is known as sexual reproduction.
• Fertilisation: The process of fusion of the male gamete with the female gamete to form a zygote is known as fertilisation.
• Internal fertilisation: When fertilisation takes place inside the body of the female, it is known as internal fertilisation.
• External fertilisation: When fertilisation takes place outside the body of the female, it is known as external fertilisation.
• Viviparous animals: The animals that give birth to young ones are called viviparous animals.
• Oviparous animals: The animals that lay eggs are called oviparous animals.
• Asexual reproduction: The mode of reproduction in which only a single parent is involved is known as asexual reproduction. 
• Binary Fission: The type of asexual reproduction, where an organism reproduces by dividing into two new individuals is known as binary fission. 

Explore NCERT Solutions of all Chapters of Class 8 Science:

Chapter 1	Chapter 2	Chapter 3
Chapter 4	Chapter 5	Chapter 6
Chapter 7	Chapter 8	Chapter 9
Chapter 10	Chapter 11	Chapter 12
Chapter 13

Download the NCERT Class 8 Science Chapter 6 Solutions PDF Here!

NCERT Solutions of Class 8 Science Chapter 6: Reproduction in Animals

Let us now explore NCERT Solutions of Class 8 Science Chapter 6 to get answers to all writing

questions in the lesson Reproduction in Animals.

Exercise Questions

1. Explain the importance of reproduction in organisms.

Soln:

The importance of reproduction in organisms is mentioned below:

• Reproduction is a process that is essential for the continuation of a species. 
• It ensures the continuation of similar kinds of individuals, generation after generation.

2. Describe the process of fertilisation in human beings.

Soln:

• The process of fusion of the male gamete with the female gamete to form a zygote is known as fertilisation.
• The male gametes or sperms are released from the male reproductive organ called the penis.
• The sperms enter the female body through the vagina.
• From there, they travel through the fallopian tubes, where they meet the eggs.
• After that, the process of fertilisation takes place in the fallopian tube.
• The male gamete cell (sperm) and female gamete cell (egg) fuse to form a zygote.
• After the zygote is formed, it undergoes division to form a ball of cells. 
• These cells start to form groups and differentiate to give rise to different tissues and organs. This developing structure is known as the embryo.
• The embryo gets embedded in the wall of the uterus and continues to develop.
• Gradually, the embryo develops all the body parts such as hands, legs, eyes, ears, etc.
• When the embryo develops body parts, it is known as a foetus.
• After the complete development of the foetus which takes about 9 months, the baby is delivered by the mother. 
• Since the gametes from both the individuals, the mother and the father, fuse to form the zygote, the new individual hence, inherits characters from both of them.

3. Choose the most appropriate answer.

(a) Internal fertilisation occurs

(i) in the female body

(ii) outside the female body

(iii) in the male body

(iv) outside male body

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

(i) fertilisation

(ii) metamorphosis

(iii) embedding

(iv) budding

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

(i) none

(ii) one

(iii) two

(iv) four

Soln:

a) (i) in the female body

b) (ii) metamorphosis

c) (iii) two

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 fertilisation takes place in the frog. ( )

(d) A new human individual develops from a cell called a 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 is a method of asexual reproduction. ( )

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

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

Soln:

a) False

b) True

c) True

d) False

e) True

f) False

g) False

h) True

i) True

j) False

5. Give the differences between a zygote and a foetus.

Soln:

Zygote:

• A zygote is formed by the fusion of male and female gametes.
• The earliest development stage of an individual is the zygote.
• It is single-celled.
• The zygote divides several times to form an embryo

Foetus

• It is the final stage of the development of an organism.
• Gradually, the embryo develops all the body parts such as hands, legs, eyes, ears, etc. and is known as a foetus
• The foetus stage occurs after the embryo stage
• In the foetus, the development is mainly internal.

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

Soln:

• The mode of reproduction in which only a single parent is involved is known as asexual reproduction. 
• The number of chromosomes remains the same.

Binary fission in amoeba:- 

• Amoeba reproduces by binary fission. 
• The type of asexual reproduction, where an organism reproduces by dividing into two new individuals is known as binary fission. 
• In this, the nucleus of the amoeba divides at first by karyokinesis.
• Then the body divides into two parts forming two amoeba from one amoeba by the process of cytokinesis. 

Budding in Hydra:- 

• Hydra reproduces by using its regenerative cells in the process of budding.
• At first, a bulge appears on the body of the hydra. 
• This is known as a bud.
• This bud develops into a new individual.
• Eventually, it separates from the parent forming a new hydra.

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

Soln:

• The embryo gets embedded in the wall of the uterus and continues to develop.
• Gradually, the embryo develops all the body parts such as hands, legs, eyes, ears, etc.
• When the embryo develops body parts, it is known as a foetus. 

8. What is metamorphosis? Give examples.

Soln:

• The transformation of a larva into an adult through various stages of change is known as metamorphosis.
• Examples:- frogs and insects.
• In the case of a frog, there are three distinct stages:- eggs → tadpole (larva) → adult frog.

9. Differentiate between internal fertilisation and external fertilisation.

Soln:

Internal fertilisation	External fertilisation
When fertilisation takes place inside the body of the female, it is known as internal fertilisation.	When fertilisation takes place outside the body of the female, it is known as external fertilisation.
In this fertilisation, the young ones formed are more protected.	In this fertilisation, the young ones formed are comparatively less protected.
The number of female gametes released is low.	The number of female gametes released is more.
Example:- humans, cows, dogs and hens.	Example:- frog, fish, starfish, etc.

10. 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 a hen.

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

Soln:

Across

1) Fertilization

6) Internal

7) Buds

8) Ovary

Down

2) Testes

3) Zygote

4) Oviparous

5) Binary

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