NCERT Solutions for Class 8 Science Chapter 10 is Reaching the Age of Adolescence. This is the best study material for those students who are finding difficulties in preparing for their exams. The NCERT Solutions for Class 8 Science reaching the age of adolescence includes the explanations to all the questions included in the CBSE class 8 textbook and are prepared by the subject professionals in a systematic manner according to the updated CBSE syllabus and guidelines.
This chapter helps to gain complete knowledge on the meaning of adolescence, changes that occur during adolescence, hormones that are released prior to adolescence, sexual maturity in male and females, menstrual cycle and its consequences.
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NCERT Solutions for Class 8 Science Chapter 10 : Reaching the Age of Adolescence
1. What is the term used for chemical secretions of endocrine glands
responsible for changes taking place in the body?
Hormones are chemical substances responsible for changes taking place in the body. They are secreted by endocrine glands.
2. Define adolescence.
Adolescence is the time period which comes between the beginning of adulthood and puberty. The body undergoes different changes alongside reproductive maturity during adolescence.
Adolescence starts somewhat at the age of 11 and ends at the age of 18 or19. This period of adolescence may differ from person to person.
3. What is menstruation? Explain.
The process of the shedding of the uterine lining on a regular monthly basis is known as menstruation.
In females, with the onset of puberty the ova or eggs begin to mature. Once in about 28 to 30 days one egg gets matured and is released by one of the ovaries. During this period, the wall of the uterus becomes thick in order to receive the fertilized egg. In case it is fertilized, it begins to develop. This results in pregnancy. But if the fertilization fails to take place, the ovum and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in women. This is called menstruation. It occurs once in 28 to 30 days.
4. List changes in the body that take place at puberty.
The changes that take place in the body at puberty are:
Shoulders get broader and muscles grow more prominently in boys.
The region below the waist becomes wider in girls.
Hair starts growing in different parts of the body of boys and girls.
Due to increased secretion of sweat and sebaceous gland, most of the teenagers get acne and pimples on their face.
Onset of puberty brings changes in secondary sexual characters in both male and female.
Boys and girls become capable of reproduction.
Menstruation starts in girls.
Different types of hormones start to release in initiating a reproductive function.
5. Prepare a Table having two columns depicting names of endocrine
glands and hormones secreted by them.
Endocrine gland Hormone
Pituitary gland Growth Hormone
Adrenal glands Adrenaline
6. What are sex hormones? Why are they named so? State their function.
The chemical substances produced by the sex organs are called sex hormones. For example, in females, the sex hormone produced by the ovary is called oestrogen and in males, the sex hormone produced by the testis is called testosterone.
The functions performed by the sex hormones are:
Oestrogen: This hormone is responsible for the development of secondary sexual characters in females like enlargement of breasts, development of female reproductive organs etc.
Testosterone: This hormone brings the secondary sex character in boys such as the growth of beard, the voice becomes hoarse, development of the reproductive organs etc.
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.
Option (iv) is the correct answer.
(b) Reproductive age in women starts when their
(i) menstruation starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.
Option (iii) is the correct answer.
(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
Option (ii) is the correct answer.
8. Write notes on—
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
(a) Adam’s apple: During puberty, a change in the voice of boys and girls takes place due to increase in the size of the voice box or larynx. In boys, the voice box tends to protrude out on the upper part of the neck, below the chin. This is referred to as Adam’s apple.
(b) Secondary sexual characters: The characters which are visible more apparently and help in distinguishing a male from a female are called secondary sexual characters. For example, in girls breasts and in boys facial hair, i.e., moustache and beard.
(c) Sex determination in the unborn baby: The sex of a child is determined at the time of fertilisation. All human beings have 23 pairs of chromosomes in the nuclei of their cells. Two chromosomes out of these are sex chromosomes. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised egg always has one X chromosome. But sperms are of two kinds—One having X chromosome, and the other having 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 or ovum at fertilisation, the zygote would develop into a male child. It is thus clear that the sex chromosome of the father determine the sex of the unborn baby.
9. Word game: Use the clues to work out the words.
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
1. Male hormone
2. Secretes thyroxine
3. Another term for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence
Solution: Refer pdf
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
From the given graph, we conclude that initially boys grow faster than girls from 0-8 years, then girls grow faster than boys from 8-16 years. But both reach their maximum height at the age of 20. Here boys show a greater increase in height than girls.