Saturday, 11 June 2016

TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VIII SCIENCE Chapter 9 Reproduction In Animals



1)Explain the importance of reproduction in organisms.

ANSWER:-Reproduction helps to carry on their generation. If reproduction does not take place, no living being will survive on the earth. Had the process of reproduction not been there then all the plants and animals would have become extinct. Secondly, special characters of an organism are carried over to its next generation through reproduction only.

2) Describe the process of fertilization in human beings.











ANSWER:-There is sexual reproduction in human beings. Male reproductive organs produce sperms (male gametes) while the female gametes produce ova (female gametes). The sperms are ejected inside female bodies where they fuse with ovum and forms zygote (called internal fertilization). The single celled zygote begins to develop into an embryo which attaches to the female uterus wall. The embryo further multiples into many cells and develops further into a small baby called foetus.

3) Choose the most appropriate answer:
(a) Internal fertilization occurs
(i) in female body.
(ii) outside female body.
(iii) in male body.
(iv) outside male body.

ANSWER: (i) in female body.

(b) A tadpole develops into an adult frog by the process of
(i) fertilization. (ii) metamorphosis. (iii) embedding. (iv) budding.

ANSWER:- (ii) metamorphosis.

c)The number of nuclei present in a zygote is
(i) none. (ii) one. (iii) two. (iv) four.

ANSWER:- one

4) Indicate whether the following statements are True (T) or False (F).
(a) Oviparous animals give birth to young ones. ( )
► False
(b) Each sperm is a single cell.( )
► True
(c) External fertilization takes place in frogs. ( )
► True
(e) Egg laid after fertilization up of a single cell. ( )
► True
(f) Amoeba reproduces by budding. ( )
► False
(g) Fertilization is necessary even in asexual reproduction.( )
► False
(h) Binary fission is a method of asexual reproduction. ( )
► True
(i) A zygote is formed as a result of fertilization. ( )
► True
(j) An embryo is made up of a single cell. ( )
► False

5)Give two difference between a zygote and a foetus.

ANSWER:-
ZYGOTE                                           FOETUS
It is a                                                   It is a stage
fertilized                                              Of the embryo
egg.                                                     that shows all the
formed                                                main recognizable
after the                                               body parts of a
fusion of                                              mature organism
the sperm
with the egg.

Zygote is single.                                  Embryo is      
cellular.                                                 multi cellular.

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

ANSWER: - Asexual reproduction is that type of reproduction in which only single parent is involved. Asexual reproduction takes place by different methods like Budding, Binary fission etc.
Budding: This type of reproduction takes place in Hydra and Bacteria. A part of the organism starts bulging out. Slowly it grows and develops into a separate individual.
Binary fission : In this type of reproduction, a single organism gets divided into two. This type of reproduction takes place in Amoeba.

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



ANSWER:- The embryo gets embedded in the wall of the uterus.

8)What is metamorphosis? Give examples.

ANSWER:-The transformation of the larva into adult through drastic changes is called metamorphosis. Frogs and insects are examples of organisms showing metamorphosis.

9)Differentiate between internal fertilization and external fertilization.

ANSWER:-
Internal fertilisation: Fusion of male and female gametes inside female body.
Chances of the survival of the offspring are more. Therefore, a small number of eggs are produced.
External fertilisation: Fusion of male and female gametes outside female body.

Chances of survival of the offspring are less. Therefore, a large number of eggs are produced
Written By Badal Paul
The author is a passionate blogger, writer and educationalist. This blog is created to ease troubles of the Cbse students. The author holds multiple blogs and the writer of the Novel KALCHAKRA, OOM AND THE CHOSEN FIVE.