8th science: Ch:Reaching the age of adolescence solution of question

CBSE Science Chapter: Reaching the age of adolescence

Q1. What is adolescence?

Ans. It is the period of life when the body undergoes changes, leading to reproductive maturity.

Q2. Define puberty.

Ans. The stage when human body becomes sexually mature.

Q3. Enlist the changes occurring in males and females during puberty.

Ans.

Type of change                                    In girls                                    In boys

Increase in height                     Sudden increase           Sudden in crease

Body shape                              Waist widens               Shoulders broadens

Voice change                           High pitched                Voice becomes deeper

Development of sex organs     Ovaries mature and      Testes matures

releases eggs.               and produces sperms

Q4.  What is adam’s apple?

Ans. The growing voice box in boys can be seen as a protruding part of the throat called adam’s apple.

Q5. What are secondary sexual characters?

Ans.These are the features that help to distinguish males from females.

Q6. Define the following terms.

Ans. 1. Hormone- they are chemical messengers for various processes and activities in the body

2. Endocrine glands- the ductless glands which secrete hormones directly into blood.

Q7. What is the role of hormones in initiating reproductive function?

Ans.  1. Hormones from pituitary stimulate testes and ovaries to release testosterone and estrogenrespectively.

3. These sex hormones reach to target sites via blood.

4. Then stimulate changes in the body at the onset of puberty.

Q8.  Discuss reproductive phase of life in women.

Ans. In females the reproductive phase of life begins at puberty and continues till they reach the age of

45-50 years. The egg begins to mature with the onset of puberty. One mature ovum is released by one of the ovaries every month. The process is called ovulation. During this period, the walls of the uterus 1become thick so as to receive fertilized egg.  Then this egg gets implanted in the uterus resulting in pregnancy.

Q9 Give reasons for the following :

a. Tadpoles growing in iodine deficient water have retarded growth.

Ans. The process of growth and development is regulated by thyroxine hormone which is produced by thyroid gland. Iodine is required for thyroxine production. That is why retarded growth is seen in tadpoles living in iodine deficient water.

b. Voice becomes hoarse in adolescent boys.

Ans. Sometimes the muscles of the growing voice box go out of control and the voice becomes hoarse.

c. Adolescents experience acne and pimples.

Ans. This is dues to increased activity of sebaceous (oil) glands in the skin.

d. Females have no role in determining gender of a child.

Ans. Y- chromosomes that leads to a boy offspring is contributed by male parent. That is thesperms are of two types, having either X or Y chromosome.

10. What are the causes of AIDS?

Ans. The causes of AIDS are:

1. Sharing needle of the syringe

2. unprotected sex with infected person.

3. blood transfusion from infected person to healthy one.

4. infected mother can pass HIV through milk to an infant.