Q51 of 130 Page 183

Define adolescence. State some of the change which take place in boys and girls during adolescence.

The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age.

The changes which take place in boys are facial and body hair growth, voice deepens, testes start to make sperms etc.


The changes which take place in girls are breast grow, ovaries start to release egg, menstruation begins etc.


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49

State whether the following statements are true or false:

(a) The estrogen hormone develops deeper voice in males at puberty.


(b) Menstruation stops in men permanently around the age of 45 to 50 years.


(c) Man (father) is responsible for the sex of the body.


(d) The sex chromosomes in all the gametes (sperms) of a man are not identical.


(e) Half the female gametes contain X chromosomes and the other half contain Y chromosomes.


(f) It is the sperm which determines the sex of a child.


(g) Each normal cell in our body contains 23 chromosomes and the other half contain Y chromosomes.


(h) A girl should not be allowed to work in the kitchen during menstruation.


(i) A woman (mother) is responsible for the sex of her child.


(j) Metamorphosis in insects (like silk moth) is brought about by thyroxine hormone.

 50

Fill in the following blanks with suitable words:

(a) Sexual maturity is reached at……………


(b) The changes which occur in boys and girls at puberty are brought about by various………….


(c) Initially, girls grow…..than boys.


(d) The changes occurring in body and mind during adolescence are a natural part of……………….up.


(e) The features which help us to distinguish between a mature boy and a girl are called………sexual characteristics.


(f) The onset of puberty is controlled by…………..


(g) Menstrual cycle in women is controlled by…………….


(h) Each normal body cell in humans contains……………..pairs of chromosomes out of which……………..pair is of sex chromosomes.


(i) X and Y chromosomes are called……….chromosomes.


(j) Early marriage and motherhood cause health problems in the ……………and the……………….


(k) The protective foods are ………. And ……………….


(l) Thyroid and adrenals secrete their hormones when they receive instructions from……..gland through its hormones.


(m) Metamorphosis in amphibians is brought about by…….hormone.

 52

What is puberty? Who attains puberty at an earlier age in human beings: male (boy) or female (girl).

 53

Write two changes that happen during puberty to: (a) both boys and girls (b) boys only (c) girls only.