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Reaching the Age of Adolescence (Biology) Class 8 - NCERT Questions
Q 1.

What is the term used for secretions of endocrine glands responsible for changes taking place in the body?

SOLUTION:

Hormones.

Q 2.

Define adolescence.

SOLUTION:

The period of life, when the body undergoes changes, leading to reproductive maturity is called adolescence.

Q 3.

What is menstruation? Explain.

SOLUTION:

When egg produced by ovary does not get fertilized, it along with the thickened lining of the uterus and blood vessels get out of the body every 28 days as bleeding in woman. This is called menstruation.

Q 4.

List the changes in the body that take place at puberty.

SOLUTION:

Certain changes take place in the bodies of boys and girls at the age of puberty. These include:
(i) Growth of hair in private body parts.
(ii) Sudden increase in height.
(iii) Growth of moustache and beard in boys.
(iv) Voice of boys get deep and that of girls become shrill.
(v) Development of breasts in girls and hips get heavy.
(vi) Development of sex organs.

Q 5.

Prepare a table having two columns depicting names of endocrine glands and hormones secreted by them.

SOLUTION:

Q 6.

What are sex hormones? Why are they named so? State their function.

SOLUTION:

Sex hormones are the hormones secreted by testes (testosterone) and ovaries (estrogen). They are called sex hormones because it distinguish different sex i.e., a boy is distinguished from a girl due to these hormones. Their function is to develop the secondary sexual characters in boys and girls.

Q 7.

Choose the correct option.
(A) Adolescents should be careful about what they eat, because
(i) proper diet develops their brains.
(ii) proper diet is needed for the rapid growth taking place in their body.
(iii) adolescents feel hungry all the time.
(iv) taste buds are well developed in teenagers.
(B) Reproductive age in woman starts when their
(i) menstruation starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.
(C) The right meal for adolescents consists of
(i) chips, noodle, coke.
(ii) chapati, dal, vegetables.
(iii) rice, noodles and burger.
(iv) vegetable cutlets, chips and lemon drink.

SOLUTION:

(A)–(ii), (B)–(i), (C)–(ii)

Q 8.

Write notes on :
(A) Adam’s apple
(B) Secondary sexual characters
(C) Sex determination in the unborn baby.

SOLUTION:

(A) At puberty, the voice box or the larynx begins to grow. Boys develop larger voice boxes. The growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple.
(B) Secondary sexual characters are the traits that distinguish the two sexes of an individual. In human beings, secondary sexual characters in males include gain in height, a prominent Adam’s apple, deep voice, growth of beard, moustaches and pubic hair, hair on the chest, thighs and armpits.
In females, the secondary sexual characters are seen as height gain, but with shorter stature than boys, less facial hair, growth of pubic hair, hair in armpits, high-pitched voice, and development of breasts. Other features include broadening of pelvis and deposition of fat around hips and smoother skin texture.
(C) The sex of the unborn baby is determined by the sex chromosome of the father. An unfertilized egg always has X chromosome. If a sperm contributes X chromosome then the baby will be a female and if the sperm contributes Y chromosome, the baby will be a male. So it is the father, who is responsible for the sex of the unborn baby.

Q 9.

Word game: Use the clues to work out the words.

Across
3. Protruding voice box in boys
4. Glands without ducts
7. Endocrine gland attached to brain
8. Secretion of endocrine glands
9. Pancreatic hormone
10. Female hormone
Down
1. Male hormone
2. Secretes thyroxine
3. Another term for teenage
5. Hormone reaches here through bloodstream
6. Voice box
7. Term for changes at adolescence

SOLUTION:

Q 10.

The table below shows the data on likely heights of boys and girls as they grow in age. Draw graphs showing height and age for both boys and girls on the same graph paper. What conclusions can be drawn from these graphs?

SOLUTION:

At birth, both girls and boys are of the same height. In further years, girls become shorter than the boys. As soon as both girls and boys reach the age of 12 years (puberty age of girls), girls become taller than the boys till the age of 15 years. At 16 years of age, both become of the same height. At the age of 20 years, again girls become shorter than the boys.