NCERT Solutions For Class 8 Science Chapter 10

Ncert Solutions For Class 8 Science Chapter 10 PDF Free Download

NCERT Class 8 Science Chapter 10 Solutions for the chapter reaching the Age of Adolescence is the best study material for those students who are finding difficulties in preparing for their exams. These materials include solutions for all the questions present in the NCERT textbooks. Students can also prepare their notes and other class assignments by downloading these solutions in pdf format for free.

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 (2018-19).

Subtopics of Class 8 Science Chapter 10 Solutions for the chapter reaching the Age of Adolescence

Section Number Topics
10.1 Adolescence and Puberty
10.2 Changes at Puberty
10.3 Secondary Sexual Characters
10.4 Role of Hormones in Initiating Reproductive Function
10.5 Reproductive Phase of Life in Humans
10.6 How is the Sex of the Baby Determined
10.7 Hormones other than Sex Hormones
10.8 Role of Hormones in Completing the Life History of Insects and Frogs
10.9 Reproductive Health

NCERT class 8 Science Reaching the Age of Adolescence Important Questions


Which chemical substance is secreted by the endocrine glands which are responsible for the changes taking place in the body?


The chemical substance secreted by the endocrine glands is called Hormones. Hormones are responsible for the changes taking place in the body.



What do you mean by the term Adolescence?


The time period which comes between the beginning of adulthood and puberty is called Adolescence. In this time period, the body undergoes different changes alongside reproductive maturity. It 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.



Define Menstruation.


The process of shedding of the uterine lining on a regular monthly basis is called menstruation. It starts at puberty and in the reproductive cycle of the female body. The uterus prepares itself to receive a fertilized egg on every month. Due to this the inner lining of the uterus become thick and is supplied with blood to nourish the embryo. If the egg is not fertilized, then the lining of the uterus breaks down and get released in the form of blood through the vagina. The time period for this is about 2 to 8 days every month. This monthly cycle is known as the menstrual cycle.



At the time of puberty, what are the changes that take place?


The changes that take place at the time of puberty are as follows:

  1. a) The height and weight of the body will suddenly increase
  2. b) The hair seems to appear in the area such as legs, hands, face and underarms
  3. c) In female, the enlargement of the ovary takes place and starts producing matured eggs and on the other hand in males, the testis grows and starts producing sperms
  4. d) In males, the shoulder broadens and chest becomes widen, whereas in females the region below the waist becomes wider.
  5. e) The acne seems to appear because of the excessive secretion of the oil from the skin.
  6. f) In boys, the larynx becomes prominent under the influence of hormones, the vocal cord becomes longer and thicker. Due to this change causes the voice to become hoarse.



Draw a table that shows the name of the endocrine glands and the hormones secreted by them.


Endocrine Glands Hormones
Testis Testosterones
Ovary Oestrogen
Pituitary Growth hormone
Adrenal Adrenalin
Thyroid Thyroxin
Pancreas Insulin



What do you mean by the sex hormones? Why are they called so and state their function?


The chemical substances produced by the sex organs are called sex hormones. For example, in females, the sex hormones produced by the ovary is called oestrogen and in males, the sex hormones produced by the testis is called testosterone.

Some of the functions performed by the sex hormones:

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.



Pick the right one out:

a) The adolescents should take care of their diets, because:

i) they feel hungry during this age

ii) in teenagers the taste buds are well developed

iii) proper diet will develop their brains

iv) for the rapid growth in the body proper diet must be needed

b) the reproductive age in women begins when their

i) breast starts developing

ii) height increases

iii) menstruation starts

iv) body weight increases

c) The right meal for adolescents consists of:

i) rice, noodles and burger

ii) chapatti, dal, vegetable

iii) chips, noodles

iv) vegetable cutlets, chips and lemon drinks


a) The adolescents should take care of their diets, because:

iv) For the rapid growth in the body proper diet must be needed.

b) The reproductive age in women begins when their

iii) Menstruation starts

c) The right meal for adolescents consists of:

ii) Chapatti, dal, vegetable



Short notes of the following:

a) Secondary sexual character

b) Adam’s apple

c) Sex determination in the unborn baby


a) Secondary sexual character is the feature which differs males from the female’s body. These can be the physical or behavioural characteristic that appears in them at the time of puberty.

In boys the secondary sexual characters are:

i) Beard and moustache grew up

ii) Chest hair grew up

iii) Hairs in the genital area grown up and other parts of the skin

In girls the secondary sexual characters are:

i) Hairs in the genital area grown up and other body parts

ii) The breast size increases and the skin of nipples present on the tip of the nipples started darkening.

b) Adam’s apple: In human males, the larynx grows the larger at the time of puberty and can be seen as a protruding part of the throat. This protrusion is known as Adam’s apple. In boys under the influence of sex hormones, the larynx becomes prominent. Due to this, the vocal cord becomes thicker and longer which causes the voice hoarse. On the other hand in females, the larynx is of small size and is hardly visible. Therefore, girls have a high pitched voice while the voice of the boys is low pitched.

c) Sex determination in the unborn baby

The fusion of the male gametes with the female gametes determines the sex of the baby. There are all 23 pairs of chromosomes in the nuclei of human beings. The last pair among the 23 is known as sex chromosome.

The human male has 23 pair of chromosomes including XY sex chromosomes. Therefore the male gametes have 22 chromosomes and either an X or Y sex chromosome.

The male gametes can be of two types: 22+X or 22+Y

Females have 23 pairs of chromosomes including XX chromosomes. Therefore, their gametes can only have 22 chromosomes and one X sex chromosomes

The type of female gametes: 22+X


Thus, as the mother provides only X chromosomes, the sex of the baby is determined by the type of male gamete (X or Y) that fuses with the X chromosomes of the female.



Word game; use the clues to work out the words.


  1. Protruding voice box in boys
  2. Glands without ducts
  3. Endocrine gland attached to a brain
  4. Secretion of endocrine glands
  5. Pancreatic hormone
  6. Female hormone


  1. Male hormone
  2. Secretes thyroxin
  3. Another term for teenage
  4. Hormone reaches here through the bloodstream
  5. Voice box
  6. The term for changes at adolescence




  1. Adam’s apple
  2. Endocrine
  3. Pituitary
  4. Hormone
  5. Insulin
  6. Estrogen


  1. Testosterone
  2. Thyroid
  3. Adolescence
  4. Target site
  5. Larynx
  6. Puberty




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



The above graph shows the relation between the age and height of both boys and girls. At the time of puberty, there is a sudden increase in height of both boys and girls. On the basis of the above graph, it can be observed that during the age of 4-8 years, girls have less height as compared to boys. However, as soon as a girl reach 12-13 years, their height shows a sudden increase and become more than boys. In later years, growth in both sexes becomes stable. Growth during puberty is under the control of hormones.

Adolescence is a transitional phase of development between childhood and adulthood. It is important to know the changes that take place in our body as we grow up. One of the frequently asked questions in the exam is the difference between puberty and adolescence. It is a wise idea to make a comparison table between the two to avoid confusion between them. All the topics in the chapter are covered in these solutions. It also comprises important questions, worksheets, exemplary problems and tips and tricks.

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