NCERT Class 8 Science Chapter 9 Solution
Brief Information: This post contains the solution for Chapter 9 Recproduction in Animals of Class 8 of the CBSE and also Gujarat Board (GSEB) books by GCERT (based on new NCERT).
Q1. Explain the importance of reproduction in organisms.
Ans. Reproduction is a process through which the individual produce new offspring. Reproduction is essential for the continuation of species. If the organism does not reproduce, the species face the threat of becoming extinct in future.
Q.2 Describe the process of fertilisation in human beings.
Ans. The fertilisation among humans occur inside the body through process of internal fertilisation. During fertilisation sperms come in contact with the egg. One of the sperm fuses with the egg. The nuclei of sperm and egg fuses and single nuclei is formed. This result in formation of fertilised egg or zygote.
Q.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.
Ans. (i) in female body.
(b) A tadpole develops into an adult frog by the process of:
(i) fertilisation
(ii) metamorphosis
(iii) embedding
(iv) budding
Ans. (ii) metamorphosis
(c) The number of nuclei present in a zygote is:
(i) none
(ii) one
(iii) two
(iv) four
Ans. (ii) one
Q.4. Indicate whether the following statements are True (T) or False (F).
1. Oviparous animals give birth to young ones. – F(False)
2. Each sperm is a single cell. – T(True)
3. External fertilisation takes place in frog. – T(True)
4. A new human individual develops from a cell called gamete. – F(False)
5. Egg laid after fertilisation is made up of a single cell. – T(True)
6. Amoeba reproduces by budding. – F(False)
7. Fertilisation is necessary even in asexual reproduction. – F(False)
8. Binary fission is a method of asexual reproduction. – T(True)
9. A zygote is formed as a result of fertilisation. –T(True)
10. An embryo is made up of a single cell. – F(False)
Q.5. Give two differences between a zygote and a foetus.
Zygote | Foetus |
(a) It consist of single cell i.e single celled. | (a) It consist of many cell i.e Multicelled. |
(b) It is formed by the fusion of male gamete or sperm and female gamete or ova (egg). | (b) It is formed by the repeated division of the zygote. |
Q.6. Define asexual reproduction. Describe two methods of asexual reproduction in animals.
Ans. Asexual reproduction is a type of reproduction that does not involve fusion of gametes. Only single parents is involved in this mode of reproduction. Asexual reproduction takes place in Amoeba, Hydra, yeast, starfish, sponges, etc. Following are two major method of sexual reproduction.
a.) Budding: In this method, one or two bulges develops of organism and they are called buds. The buds develop into new individual. Budding is seen in Hydra.
b.) Binary Fission: In this method, the nuclei of single celled organism divides into two nucleus. Later, division of body of organism takes place. Two new individuals are produced from single parent. Binary fission occur in Amoeba
Q.7. In which female reproductive organ does the embryo get embedded?
Ans. The embryo gets embedded in female reproductive organ called Uterus.
Q.8. What is metamorphosis? Give examples.
Ans. Metamorphosis is a biological process in which drastic changes occur in larvae of animal and it transforms into adult. E.g. Butterfly, frog etc
Q.9. Differentiate between internal fertilisation and external fertilisation.
Internal Fertilisation | External Fertilisation |
(a) The fusion of egg and sperms which takes place inside th body of female organism is called Internal Fertilisation | (a) The fusion of egg and sperms which takes place outside th body of female organism is called External Fertilisation |
(b) The female partner either lays fertilised eggs or gives birth to a fully grown young one. | (b) The female partner discharges unfertilised eggs. |
(c) The offsprings have higher survival rate i.e high chance of survival. | (c) Offsprings have a low chance of survival. |
(d) E.g. Humans, Birds, Mammals etc | (d) E.g. frog, fish, starfish etc |
Q.10. Complete the following word puzzle with the help of clues given below.
Down
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 Hydra.
8. Eggs are produced here.
Across
2. Sperms are produced in these male reproductive organs
3. Another term for the fertilised egg.
4. These animals lay eggs.
5. A type of fission in Amoeba.
Ans.
Down
1. The process of the fusion of the gametes. – Fertilisation
6. The type of fertilisation in a hen. – Internal
7. The term used for bulges observed on the sides of the body of Hydra. – Buds
8. Eggs are produced here. – Ovary
Across
2. Sperms are produced in these male reproductive organs. – Testes
3. Another term for the fertilised egg. – Zygote
4. These animals lay eggs. – Oviparous
5. A type of fission in Amoeba. – Binary