NCERT Solutions for Class 8 Science Chapter 10 Reaching the age of Adolescence

NCERT Solutions for Class 8 Science Chapter 10 Reaching the age of Adolescence will make your memory skills sharper and you can easily memorize more things. Student can rely on these answers as they come from experts who have been teaching for quite some time and know what’s expected in the test papers.

Chapter 10 CBSE Class 8 Science NCERT Solutions are written in detail by people who have expertise in the field and the entire chapter has been explained in a very simple yet in-depth manner. You develop the skills necessary to answer the tough questions that you’re faced with.

Chapter 10 Reaching the age of Adolescence Class 8 Science NCERT Solutions

Exercises

1. What is the term used for secretions of endocrine glands responsible for changes taking place in the body?

Solution

Hormones

2. Define adolescence.

Solution

Adolescence is the transitional period in a person’s life between childhood and adulthood. It typically includes physical and psychological changes, as well as social and emotional development. It begins at the age of 11 years and ends between the age of 18 to 19 years.

3. What is menstruation? Explain.

Solution

Menstruation is discharging of blood from uterus through vagina once in about 28-30 days. The menstrual cycle involves the discharge of blood from the uterus through the vagina once every 28-30 days. As the uterus wall and blood vessels separate, blood drains out and a new uterine wall is formed.

4. List changes in the body that take place at puberty.

Solution

The changes in the body that take place at puberty are:

• The most noticeable change is the increase in the height of adolescents.
• The voice box or the larynx grows during puberty resulting in a change in voices of both the boys and girls.
• In male, hormone testosterone begins to release by the testes and starts producing sperms.
• In female, the ovaries start producing the female hormones. As a result, the ovaries enlarge and start releasing eggs.
• In males, the shoulder broadens and chest become widen, whereas in females the pelvic region widens, hips broaden, breasts develop and increase in size.
• The acne is seems to appear because of the excessive secretion of the oil from the skin.

5. Prepare a table having two columns depicting names of endocrine glands and hormones secreted by them.

Solution

Endocrine gland	Hormones
Testes	Testosterone
Ovary	Estrogen
Thyroid	Thyroxin
Adrenal	Adrenalin
Pancreas	Insulin
Pituitary	Growth hormone

6. What are sex hormones? Why are they named so? State their functions.

Solution

Testosterone and estrogen are called sex hormones. Testosterone is the male hormone secreted by testes at the start of puberty. Estrogen is the female hormone secreted by ovaries. It makes the egg mature. These hormones help in the development of secondary sexual characters and hence are called sex hormones.

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.
▶ (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
(ii) Breasts start developing
(iii) Body weight increases
(iv) Height increases
▶ (i) Menstruation starts

(c) The right meal for adolescents consists of:
(i) Chips, noodles, coke
(ii) Chapatti, dal, vegetables
(iii) Rice, noodles and burger
(iv) Vegetable cutlets, chips and lemon drink
▶ (ii) Chapatti, dal, vegetables

8. Write notes on:
(a) Adam’s apple
(b) Secondary sexual characters
(c) Sex determination in the unborn baby

Solution

(a) Adam’s Apple: It is the protruding part of the throat in boys is the growing voice box.
(b) Secondary sexual characters: Secondary sexual characters are characteristics that identify a man from a woman. Males have secondary sexual characters such as growing hair on the face, chest, under arms, and pubic region. Secondary sexual characters in females include developing breasts and growing hair under the armpits and pubic region.
(c) Sex determination in the unborn baby: Unborn children are classified as either male or female based on their chromosomes. A zygote with one X and one Y chromosome develops into a male child. An unborn child with two X chromosomes develops into a female child.

9. Word game: Use the clues to work out the words.

Across
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

Down
1. Male hormone
2. Secretes thyroxin
3. Another term for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence

Solution

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

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

Solution

From the graph, we can see that girls are typically taller than boys at 12 years of age. At 16 years of age, both are about the same height, but eventually boys gain height and become taller.