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

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

Question 3. Define Menstruation.
Solution : The process of shedding of the uterine lining on regular monthly basis is called as 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 form of blood through vagina. The time period of this is about 2 to 8 days every month. This monthly cycle is known as menstrual cycle.

Question 4. At the time of puberty what are the changes that takes place?
Solution :
The changes that take place at the time of puberty are as follows:
a) The height and weight of the body will suddenly increases
b) The hair seems to be appear in the area such as legs, hands, face and underarms
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
d) In males the shoulder broadens and chest become widen, whereas in females the region below the waist become wider.
e) The acne is seems to appear because of the excessive secretion of the oil from the skin.
f) In boys, the larynx become prominent under the influence of hormones, the vocal cord become longer and thicker. Due to this change causes the voice to become hoarse.

Question 5. Draw a table that shows the name of the endocrine glands and the hormones secreted by them.
Solution :

Endocrine GlandsHormones
PituitaryGrowth hormone

Question 6. What do you mean by the sex hormones? Why are the called so and state their function.
Solution : Sex hormones are chemical substances produced by sex organs. For example, testosterone is the male sex hormone produced by the testis, and oestrogen is the female sex hormone produced by the ovary. These hormones are secreted by sex organs and affect the sexual features of an organism. Hence, they are known as sex hormones.
Functions of sex hormones:
Testosterone: This hormone brings about secondary sexual characters in boys such as the growth of a beard, the voice becoming hoarse, development of reproductive organs, etc.
Oestrogen: This hormone is responsible for the development of secondary sexual characters in females such as the enlargement of breasts, development of female reproductive organs, etc.

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.
(b) Reproductive age in women starts when their
   (i) Menstruation start.
   (ii) Breast start developing
   (iii) Body weight increases
   (iv) Height increases.
(c) The right meal for adolescents consist of
   (i) Chips, noodles, coke.
   (ii) Chapatti, dal, vegetables.
   (iii) Rice, noodles and burger.
   (iv) Vegetables cutlets, chips and lemon drink.

Solution :
(a) (ii) Proper diet is needed for the rapid growth taking place in their body.
(b) (i) menstruation starts.
(c) (ii) Chapatti, dal, vegetables.

Question 8. Write notes on-
(a) Adam’s apple.
(b) Secondary sexual charecters.
(c) Sex determination in unborn baby.

Solution :
(a) Adam’s apple: At puberty, the voice box or the larynx begins to grow. The growing voice box in boys can be seen a protruding part of the throat called Adam’s apple.
(b) Secondary sexual characters: Those changes that take place at puberty in boys and girls are called secondary sexual characters. In includes increase in size of breast in girls and pubic hairs around genital organ in girls. In boys facial hair and cracking of voice are secondary sexual features.
(c) Sex determination in the unborn baby: Human beings have 23 pairs of chromosome. One pair of male (XY) and one pair of chromosome in female (XX) are called sex chromosome. Male produce two types of gametes half containing X chromosome and half containing Y chromosome. When the sperm containing Y chromosome fuse with egg the sex of baby is male and when X chromosome containing sperm fertilse the egg the sex of baby is female.

Question 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 thyroxin
   3. Another term for teenage
   5. Hormone reaches here through blood stream
   7. Term for changes at adolescence
ncert solution
Solution :
    3. Adam’s apple
    4. Endocrine
    5. Pituitary
    6. Hormone
    7. Insulin
    8. Estrogen

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

Question 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?
             Age                   Height (cm)
            (Years)              Boys      Girls
               0                      53           53
               4                     96            92
               8                    114          110
              12                  129          133
              16                  150          150
              20                  173          165

Solution :
Following are the conclusions which can be drawn from the graph:
(i) As the age increases, there is an increase in the height of both boys and girls.
(ii) Until 0 – 8 years, girls have less height in comparison to that of boys.
(iii) However from 12 – 16 years, there is sudden increase in the height of girls and becomes more than the boys.
(iv) At age of 20, boys are taller than girls.
ncergt solution

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