NCERT Solutions for Class 8 Science Chapter 10 - Reaching the Age of Adolescence

Question 1:

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



Question 2:

Define adolescence.


The period during which the human body undergoes changes leading to reproductive maturity is called adolescence. It begins at the age of 11 years and ends between the age of 18 to 19 years.

Question 3:

What is menstruation? Explain.


In females, an ovum matures and is released by one of the ovaries once in about every 28 to 30 days. If the egg is not fertilized by a sperm, it is released out from the body along with the thickened lining of the uterus. This causes monthly bleeding in women and is called menstruation.

Question 4:

List changes in the body that take place at puberty.


The following changes take place in the body at puberty:

Question 5:

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


Question 6:

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


Testosterone and estrogen are called sex hormones. Testosterone is the male hormone secreted by testes at the start of puberty. Estrogen is the female hormone secreted by ovaries. It makes the egg mature. These hormones help in the development of secondary sexual characters and hence are called sex hormones.

Question 7:

Adolescents should be careful about what they eat, because

  1. proper diet develops their brains.
  2. proper diet is needed for the rapid growth taking place in their body.
  3. adolescents feel hungry all the time.
  4. taste buds are well developed in teenagers.

proper diet is needed for the rapid growth taking place in their body.

Question 8:

Reproductive age in women starts when their

  1. menstruation starts
  2. breasts start developing
  3. body weight increases
  4. body weight increases

menstruation starts

Question 9:

The right meal for adolescents consists of

  1. chips, noodles, coke
  2. chapatti, dal, vegetables
  3. rice, noodles and burger
  4. vegetable cutlets, chips and lemon drink

chapatti, dal, vegetables

Question 10:

Write notes on:
(a) Adam’s apple
(b) Secondary sexual characters
(c) Sex determination in the unborn baby


(a) Adam’s Apple: The protruding part of the throat in boys is the growing voice box. It is called the Adam’s apple.
(b) Secondary sexual characters: Features which help in distinguishing a man from a woman are called secondary sexual characters. In males, the secondary sexual characters are growth of hair on face, chest, under arms and pubic region. In females, the development of breasts and growth of hair in the under arm and pubic regions are the secondary sexual characters.
(c) Sex determination in the unborn baby: The sex of an unborn child depends on whether the zygote has XX or XY chromosomes. If the zygote has one X and one Y chromosome, it develops into a male child. On the other hand, if the zygote has two X chromosomes, it develops into a female child.

Question 11:

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


Question 12:

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


The graph is given below:

It can be seen from the graph that girls at the age of 12 are generally taller than boys. While at 16 years, the height of both is the same but eventually boys gain height and become taller than girls.