NCERT Solutions for Class 8 Science Chapter 10 Reaching the Age of Adolescence are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 10 Reaching the Age of Adolescence.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 10
Chapter Name Reaching the Age of Adolescence
Number of Questions Solved 9
Category NCERT Solutions

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

NCERT TEXTBOOK EXERCISES

Question 1.
What is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body?
Answer.
The term used for secretions of endocrine glands is hormones, which are responsible for various changes taking place in the body.

Question 2.
Define adolescence.
Answer.
The period of life when the body undergoes changes, leading to reproductive maturity is called adolescence.

Question 3.
What is menstruation? Explain.
Answer.
When the uterus receives the egg and it is fertilized, pregnancy occurs. If fertilization does not occur, the released egg and the thickened lining of the uterus along with its blood vessels are shed off: This causes bleeding in women, which is called menstruation.

Question 4.
List changes in the body that take place at puberty.
Answer.
The onset of puberty brings about:

  1. Growth of the reproductive organs which begin to function.
  2. Hair grows at various places of the body. Breasts develop in girls and facial hair (mustache and beard) appear in boys.
  3. The voice of the boys becomes hoarse as the voice box enlarges during adolescence.

Question 5.
Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.
Answer.

Column A Column B

Name of endocrine glands

(i)Testes

(ii)Ovaries

Name of hormones

Testosterone (male)

Estrogen (female)

Pituitary glands

(iii)Thyroid

(iv) Adrenal glands

(v) Pancreas

Sex hormones and brain hormones

Thyroxine

Adrenalin

Insulin

Question 6.
What are sex hormones? Why are they named so? State their function.
Answer.
Hormones secreted by testes and ovaries are termed as sex-hormones.

  • They are named so because they are secreted by the reproductive organs.

Functions of sex-hormones.

  • These hormones are responsible for the secondary sexual characters of males and females.

Question 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.
Answer.
(ii) proper diet is needed for the rapid growth taking place in their body. Reproductive age in women starts when their

(b) Reproductive age in women starts when their
(i) menstruation starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.
Answer.
(i) menstruation starts.

(c) The right meal for adolescents consists of
(i) chips, noodles, coke.
(ii) chapati, dal, vegetables.
(iii) rice, noodles and burger.
(iv) vegetable cutlets, chips and lemon drink.
Answer.
(ii) Chapati, dal, vegetables.

Question 8.
Write notes on:

  1. Adam’s apple.
  2. Secondary sexual characters.
  3. Sex determination in the unborn baby.

Answer.

  1. At puberty, the voice box or the larynx begins to grow. The growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple. This makes a boy’s voice hoarse.
  2. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, mustaches and beards. As these features help to distinguish the male from the female, they are called secondary sexual characters.
  3. Sex Determination in the Unborn Baby: All human beings have 1 pair of sex chromosomes, as the names X and Y. A female has two X chromosomes,

Chap 10 1

while male has one X and one Y chromosome. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote, that will have ‘XT would develop into a male child. Now you know that the sex chromosomes of the father determine the sex of a baby.

Question 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 the bloodstream
6. Voicebox
7. Term for changes at adolescence.
Answer.
Chap 10 2

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