Question 1. What is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body?
Solution 1. Hormones is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body.
Question 2. Define adolescence.
Solution 2. The transition from adulthood to puberty is called adolescence. During this time period, the physical and emotional changes are at their peak. This period of time leads to the reproductive maturity of the body. Adolescence starts at the age of around 11 and ends at 18 or 19. The age of adolescence is different for everyone.
Question 3. What is menstruation? Explain
Solution 3. At the time of puberty, the uterine lining starts to shed on a regular basis is called menstruation. Every month the uterus receives a fertilized egg. To nourish the embryo the inner lining of the uterus becomes thick and is supplied by the blood. If the process of fertilization fails to take place means if the egg is not fertilized then the lining of the uterus breaks down and gets released in the form of blood through the vagina. Menstruation occurs for about 2 to 8 days every month.
Question 4. List changes in the body that take place during puberty
Solution 4. Following are the changes that take place at the time of puberty:
- Sudden increment in height and weight of the body.
- Hair growth is visible in some of the body parts of boys and girls such as legs, hands, face and underarms.
- Females start producing matured eggs and male starts producing sperms.
- In boys, muscles grow prominently and in girls also the area below the waist becomes wider.
- At this stage boys and girls become able to reproduce.
- Girls start menstruating.
- The Voice of boys changes prominently.
Question 5. Prepare a Table having two columns depicting the names of endocrine glands and hormones secreted by them.
Solution 5.
| Endocrine Glands | Hormones |
| Testis | Testosterone |
| Ovary | Oestrogen |
| Pituitary | Growth hormone |
| Adrenal | Adrenalin |
| Thyroid | Thyroxin |
| Pancreas | Insulin |
Question 6. What are sex hormones? Why are they named so? State their function
Solution 6. Sex hormones are the chemical substances produced by sex organs. Oestrogen is the sex hormone produced by the ovary in females and testosterone is the sex hormone produced by the testis in males.
The following are the function of these sex hormones:
Oestrogen: Secondary sexual characteristics in females start to develop in females because of this hormone-like enlargement of breasts, development of female reproductive organs, etc.
Testosterone: The secondary sex character in boys such as the growth of a beard, a voice becoming hoarse, development of the reproductive organs etc. occurs because of this hormone.
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 starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.
(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.
Solution 7.
a). Adolescents should be careful about what they eat, because
Ans. (ii) proper diet is needed for the rapid growth taking place in their body.
b) Reproductive age in women starts when their
Ans. (i) menstruation starts.
c) The right meal for adolescents consists of
Ans. (ii) chapati, dal, vegetables.
Question 8. Write notes on—
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
Solution 8.
a). Adam’s apple:
During puberty, the voice of boys and girls changes because of the increased size of the larynx. The larynx seems to protrude out on the outer part of the neck. This protrusion is knowns as Adam’s apple. Usually, it is seen in males which causes the voice to hoarse. In females, the larynx is of small size. Therefore, the voices of males and females are different from each other males have a deep voice and the other hand females have a high-pitched voice.
b) Secondary sexual characters: secondary sexual characters are those characters which usually appear during the phase of puberty. The male and female bodies are distinguishable from each other because of secondary sexual characteristics.
Secondary sexual characteristics are seen in males: Hoarseness of voice, the appearance of a beard, broadness of chest, and growth of hair in genital areas.
Secondary sexual characteristics are seen in females: Start of the menstrual cycle, growth of breast, and growth of hair in the genital areas.
c) Sex determination in the unborn baby: The pair of sex chromosomes that are present in the cells of the baby decides the sex of an unborn baby.
X and Y chromosomes are the sex chromosomes in humans are X and Y chromosomes. Ovum always contains an X chromosome; male sperm may carry either an X chromosome or Y chromosome. The zygote having X-X chromosomes would develop into a female child. The zygote having X-Y chromosomes would develop into a male child.