In-text Questions and Answers:
1. What is the name of the period between childhood and adulthood?
Answer: The period between childhood and adulthood is called adolescence.
2. Why do some body parts seem out of proportion during adolescence?
Answer: During adolescence, different parts of the body grow at different rates. This means your arms or legs might grow faster than the rest of your body, but eventually, everything evens out.
3. Why do boys sometimes have a hoarse voice during adolescence?
Answer: Boys may have a hoarse or cracking voice during adolescence because their voice box, or larynx, is growing bigger. This change makes their voice deeper.
4. What determines whether a baby will be a boy or a girl?
Answer: The sex of a baby is determined by the chromosomes from the parents. If the baby has two X chromosomes (XX), it will be a girl. If it has one X and one Y chromosome (XY), it will be a boy.
5. Do other animals have hormones, and do they affect reproduction?
Answer: Yes, other animals also have hormones. Hormones in animals help control growth, development, and reproduction, just like in humans.
6. Can lack of iodine in the diet cause goitre due to lack of thyroxine?
Answer: Yes, if people don’t get enough iodine in their diet, their thyroid gland can’t make enough thyroxine hormone, which can lead to a swelling in the neck called goitre.
7. Is it correct that a woman’s reproductive life lasts from menarche to menopause?
Answer: Yes, a woman’s reproductive life starts with her first menstruation (menarche) and ends when menstruation stops permanently (menopause).
Exercise Questions and Answers:
1. What are the chemicals called that are released by endocrine glands and cause changes in the body?
Answer: These chemicals are called hormones.
2. Define adolescence.
Answer: Adolescence is the period of life when a child develops into an adult. During this time, the body goes through many changes and becomes capable of reproduction.
3. What is menstruation? Explain.
Answer: Menstruation is the monthly process in girls and women where the lining of the uterus sheds and comes out as blood if there is no pregnancy. It usually happens every 28 to 30 days.
4. List changes in the body that take place at puberty.
Answer:
- Increase in height
- Change in body shape
- Growth of hair under arms and in the pubic area
- Voice changes (deeper voice in boys)
- Development of breasts in girls
- Start of menstruation in girls
- Growth of reproductive organs
5. Prepare a table showing names of endocrine glands and hormones they secrete.
Answer:
| Endocrine Gland | Hormone Secreted |
|---|---|
| Pituitary Gland | Growth Hormone |
| Thyroid Gland | Thyroxine |
| Pancreas | Insulin |
| Adrenal Glands | Adrenaline |
| Testes (in boys) | Testosterone |
| Ovaries (in girls) | Estrogen |
6. What are sex hormones? Why are they named so? State their function.
Answer: Sex hormones are chemicals produced by the sex organs (testes in boys and ovaries in girls). They are called sex hormones because they control the development of sexual characteristics. In boys, testosterone makes facial hair grow and voice deepen. In girls, estrogen helps develop breasts and start menstruation.
7. Choose the correct option.
a) Adolescents should be careful about what they eat because:
- (ii) Proper diet is needed for the rapid growth taking place in their body.
b) Reproductive age in women starts when their:
- (i) Menstruation starts.
c) The right meal for adolescents consists of:
- (ii) Chapati, dal, vegetables.
8. Write notes on:
a) Adam’s apple.
Answer: The Adam’s apple is the bump in the throat that becomes visible in boys during puberty. It’s caused by the growth of the voice box (larynx), which makes the voice deeper.
b) Secondary sexual characters.
Answer: Secondary sexual characters are features that appear during puberty which distinguish boys and girls. In boys, this includes facial hair and a deeper voice. In girls, this includes the development of breasts and wider hips.
c) Sex determination in the unborn baby.
Answer: The sex of a baby is determined by the chromosomes it inherits. An X chromosome from the mother and an X from the father make a girl (XX). An X from the mother and a Y from the father make a boy (XY).
9. Word Game Answers:
Across
- Protruding voice box in boys – Adam’s apple
- Glands without ducts – Endocrine
- Endocrine gland attached to brain – Pituitary
- Secretion of endocrine glands – Hormones
- Pancreatic hormone – Insulin
- Female hormone – Estrogen
Down
- Male hormone – Testosterone
- Secretes thyroxine – Thyroid
- Another term for teenage – Adolescence
- Hormone reaches here through bloodstream – Target site
- Voice box – Larynx
- Term for changes at adolescence – Puberty
10. What conclusions can be drawn from the graphs showing height and age for boys and girls?
Answer: The graphs show that girls usually grow faster than boys between the ages of 8 and 13. However, boys continue growing for a longer time and often become taller than girls by age 18 or 20.