NCERT solutions class 8 science chapter 9 is Reproduction in animals. It is a very crucial resource for the CBSE class 8 students. The reproduction in animal’s solutions is provided here to help class 8 students to get knowledge on the topic and to prepare for their examination effectively.
Answers provided here shed light on modes of animal reproduction, reproductive organs, sexual mode of reproduction, asexual mode of reproduction, fertilization and its types, binary fission and budding modes of asexual reproduction.
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NCERT Solutions for Class 8 Science Chapter 9 : Reproduction in Animals
1. Explain the importance of reproduction in organisms.
Reproduction is a vital phenomenon on this planet earth. Reproduction is essential for existence and continuity of life and species, generation after generation.
2. Describe the process of fertilisation in human beings.
Fertilization involves the fusion of the male and female gametes. These gametes are released from the male and the female reproductive organs. Sperms or male gametes are released from the male reproductive organ i.e., the penis. These sperms then enter the female body through the vagina. The sperms then travel through the fallopian tubes where they fuse with eggs. Hence, the process of fertilization takes place in the fallopian tubes.
3. 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.
Option (i) is the correct answer.
(b) A tadpole develops into an adult frog by the process of
Option (ii) is the correct answer.
(c) The number of nuclei present in a zygote is
Option (iii) is the correct answer.
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 frog. ( )
(d) A new human individual develops from a cell called 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. ( )
(a) Oviparous animals give birth to young ones. (F)
(b) Each sperm is a single cell. (T)
(c) External fertilisation takes place in frog. (T)
(d) A new human individual develops from a cell called gamete. (F)
(e) Egg laid after fertilisation is made up of a single cell. (T)
(f) Amoeba reproduces by budding. (F)
(g) Fertilisation is necessary even in asexual reproduction. (F)
(h) Binary fission is a method of asexual reproduction. (T)
(i) A zygote is formed as a result of fertilisation. (T)
(j) An embryo is made up of a single cell. (F)
5. Give two differences between a zygote and a foetus.
It is the earliest stage of development.
It is a single cell resultant of fusion of
ovum and sperm.
Foetus It is the last stage of development of an
organism. It is a much developed from of zygote which has body parts and organs.
6. Define asexual reproduction. Describe two methods of asexual
reproduction in animals.
A mode of reproduction in which only one parent is involved is known as asexual
reproduction. Sex cells (gametes) are not produced and no fusion of gametes takes place for the reproduction of zygote or offspring’s in asexual reproduction. Amoeba, Hydra, yeast, sponges, etc reproduce through asexual reproduction.
There are mainly two methods of asexual reproduction:
(i) Binary fission: In binary fission, a single parent cell is divided into two equal individual cells. As in amoeba where it divides into two by division of their bodies, each of them gets one nucleus and develops into separate individual. The figure given below shows how binary fission occurs in Amoeba
(ii)Budding in hydra: Organisms such as hydra, use regenerative cells for reproduction in the process of budding. The first step is the formation of buds. The bud receives the characteristics of the parent organism as it enlarges. Once it is developed, it may be detached from the parent body and develop into a new individual. In some cases, the buds may not be detached forming interconnected buds. There are also methods like fragmentation, multiple fission etc.
7. In which female reproductive organ does the embryo get embedded?
The embryo gets embedded in the uterus of the female reproductive system.
8. What is metamorphosis? Give examples.
Metamorphosis is defined as the process by which an animal’s body structure abruptly changes through cell growth and differentiation. It is a biological process.
Example of metamorphosis is the life cycle of a frog:
The tadpole which emerges from the egg will have gills, tail etc.
It can swim easily in water.
It undergoes abrupt changes and develops into a mature frog.
9. Differentiate between internal fertilisation and external fertilisation.
Takes place inside the female body,.
There are high chances of the survival of
the offspring. Example: cow, human, etc.
External fertilization Takes place outside the female body. There are low chances of the survival of the offspring. Examples: frogs, fishes, etc.
10. Complete the crossword puzzle using the hints given below.
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.
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.