NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animals Questions and Answers
Q.1 Explain the importance of reproduction in organisms.
Solution:- Importance of reproduction in organisms are:-
- Reproduction ensures the continuity of a species.
- It also maintains the number of individuals in a population.
- It is also responsible for various organisms in a population that help them to survive in the environment.
Q.2 Describe the process of fertilisation in human beings.
Solution:- Fusion of a sperm and an ovum is called fertilization. In human beings, the process of fertilization takes place in the oviducts. The sperms produced by testies in male’s body are transferred into the female’s body.
In a female’s body, one mature ovum is released into the oviduct by one of the ovaries every month. In the oviduct the sperm comes in contact with the ovum and fuses with it.
During the process of fusion, the nuclei of the sperm and ovum fuse to form one single nucleus. This results in the formation of zygote.
Q.3 Choose the most appropriate answer.
- Internal fertilisation occurs
I) in a female Body.
II) outside the female body.
III) in male body.
IV) outside the male body.
Answer is (I) in a female body
- A tadpole develops into an adult frog by process of
Answer is (II) metamorphosis
- The number of nuclei present in a zygote is
Answer is(II) one
Q.4 Indicate whether the following statements are True(T) or False(F).
- Oviparous animals give birth to young ones. ()
- Each sperm is a single cell. ()
- External fertilization takes in frogs. ()
- A new human individual develops from a cell called gamete.()
- Egg laid after fertilisation is made up of a single cell. ()
- Amoeba reproduces by budding.()
- Fertilization is necessary even in asexual reproduction.()
- Binary fission is a method of asexual reproduction.()
- A zygote is formed as a result of fertilization.()
- An embryo is made up of a single cell.()
Q.5 Give two differences between a zygote and a foetus.
|It is unicellular; hence, no well-defined body parts.||It is multicellular and has well-defined body parts.|
|II. It forms due to the fertilisation of sperm and the ovum.||II. It forms after the process of fertilization in which zygote multiplies groups into multicellular cells.|
Q.6 Define asexual reproduction. Describe two methods of asexual reproduction in animals.
Solution:- Asexual reproduction is a type of reproduction in which only one parent is involved and the off-spring is genetically identical to the parent cell.
Two methods of asexual reproduction are :-
- Binary fission
Budding – In this type of a sexual reproduction and outgrows appears on the parents body. This outgrow is termed a bud. The bud gradually grows into a small individual and then detaches itself from the parents’ body. It continues to grow and live as a new individual in the environment.
Binary fission- In this type of asexual reproduction, the nucleus of the parent’s body is divided into two nuclear after that the body is divided into two nuclei. After that, the body divides into two and each body part receives a nucleus.
Example – Amoeba
Q.7 In which female reproductive organ does the embryo get embedded?
Solution:- Embryo gets embedded in the walls of the uterus. In the uterus, the embryo grows and develops all the body parts. Then it is called a foetus.
Q.8 What is metamorphosis? Give examples.
Solution:- Metamorphosis is a biological process of transformation of an immature form such as larva into an adult through drastic changes . It is asexual in frogs (transformation of tadpole into adult frog) and insectes (transformation of silkworm into moths or butterflies).
Metamorphosis in frogs.
Q.9 Differentiate between internal fertilisation and external fertilisation.
Solution:- Difference between internal and external fertilization are as follows:-
|Characters||Internal fertilization||External fertilization|
|Site of Fertilization||Fertilization occurs inside the female body||Fertilization occurs outside the female body|
|No. Of eggs/off-spring produced||II. Less eggs are produced offspring||II. Large amount of egg is produced offspring|
|Chances of survival of eggs/ offspring||III. High chances of survival of eggs offspring||III. Low chances of survival of eggs offspring|
|Example:-||Occurs mostly in mammals||Generally occurs in fish, frogs etc.|
Q.10 Complete the crossword puzzle using the hints given below.
- 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.
- Sperms are produced in these male reproductive organs.
- Another term for in vitro fertilisation.
- These animals lay eggs.
- A type of fission in amoeba.