Sunday, June 19, 2022

Class 10 Science | Chapter-end Exercise & Answers | Chapter 8 | How do Organisms Reproduce?

1.   Asexual reproduction takes place through budding in

(a) amoeba                             

(b) yeast

(c) plasmodium                      

(d) leishmania


Answer:

(b) Yeast


2.   Which of the following is not a part of the female reproductive system in human beings?

(a) Ovary                                  

(b) Uterus

(c) Vas deferens                     

(d) Fallopian tube


Answer:

(c) Vas deferens


3.   The anther contains

(a) sepals                                

(b) ovules

(c) carpel                                 

(d) pollen grains


Answer:

(d) Pollen grains


4.   What are the advantages of sexual reproduction over asexual reproduction?


Answer:

Sexual reproduction can generate more variations and speed up the making of new variants by combining DNA copies from two individuals. All these variations are accumulated and inherited from generation to generation. It produces individuals with different patterns of variations in a population. Thus the organism can adapt quickly to changes in its surroundings.


5.   What are the functions performed by the testis in human beings?


Answer:

·   Testes produce male gametes (sperms).

· Testes produce a hormone called testosterone. It controls the development of reproductive organs and secondary sexual characters.


6.   Why does menstruation occur?


Answer:

If the ovum is not fertilised, the thick and soft inner lining of uterus is no longer needed and hence breaks. So, the lining along with the blood vessels and the dead ovum comes out of the vagina in the form of blood. This is called menstruation.


7.   Draw a labelled diagram of the longitudinal section of a flower.


Answer:

8.   What are the different methods of contraception?


Answer:

a) Barrier method: E.g., condom, diaphragm and cervical caps. These prevent the entry of sperms in the female genital tract.

b) Chemical method: Use of oral and vaginal pills. The oral pills suppress the release of ovum. The vaginal pills/ creams are spermicidal.

c) Intrauterine contraceptive devices: E.g., Copper-T. It prevents the sperms to reach the uterus.

d) Surgical method: It includes vasectomy in males and tubectomy in females. In vasectomy, a small part of vas deferens is cut or tied. In tubectomy, fallopian tube is cut or tied.


9.   How are the modes for reproduction different in unicellular and multicellular organisms?


Answer:

Reproduction mode in unicellular organisms

Reproduction mode in multicellular organisms

Asexual reproduction.

Asexual or Sexual.

Only one parent is needed.

For sexual reproduction, two parents are needed.

No special cells.

Special cells are present.

No special organs are present for reproduction.

Special organs are present for reproduction.


10.  How does reproduction help in providing stability to populations of species?


Answer:

Reproduction helps to generate copies of individuals which are suited to a particular environment.

The formation of variations during reproduction provides stability to the populations to adapt various environmental conditions.


11.  What could be the reasons for adopting contraceptive methods?


Answer:

·    To control the birth rate and population explosion.

·    To reduce the adverse effects on mother’s body due to frequent pregnancy.

·    To prevent sexually transmitted diseases.


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