Class 8 Science chapter 7 question answer Reaching the Age of Adolescence

Reaching the Age of Adolescence class 8 questions and answers: Science Class 8 chapter 7 question answer

Textbook	Ncert
Class	Class 8
Subject	Science
Chapter	Chapter 7
Chapter Name	Reaching the Age of Adolescence ncert solutions
Category	Ncert Solutions
Medium	English

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

Answer 1: The term used for chemical secretions of endocrine glands responsible for changes in the body is hormones. Hormones are chemical messengers that regulate various physiological processes, such as growth, metabolism, mood, and reproduction.

Question 2: Define adolescence.

Answer 2: Adolescence is the period of life between childhood and adulthood, typically occurring between the ages of 10 and 19. During adolescence, individuals undergo significant physical, emotional, and psychological changes as they transition from being dependent children to more independent adults.

It includes the development of secondary sexual characteristics, changes in body structure, cognitive growth, and emotional maturation. Adolescence is also a time of exploration, identity formation, and greater social independence.

Question 3: What is menstruation? Explain.

Answer 3: The process of shedding 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 becomes 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 gets 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.

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

Answer 4: The following are the changes that occur throughout puberty:

• a) The body’s weight and height will increase abruptly
• b) The legs, hands, face, and underarms tend to be the places where hair seems to grow.
• c) The ovary develops larger in females and begins to produce mature eggs; in contrast, the testis expands and begins to produce sperm in males.
• d) The shoulder widens and the chest expands in men, while the area below the waist expands in women.
• g) Excessive oil secretion from the skin appears to be the cause of acne.
• f) Hormones cause the larynx to become more noticeable in boys, and the vocal chord thickens and lengthens, giving them a gruff voice.

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

Answer 5: Table showing names of endocrine glands and hormones secreted by them is as below,

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

Question 6: What are sex hormones? Why are they named so? State their function.

Answer 6: The hormones which help and control the formation of secondary sexual characters are called sex hormones. They are named so because they control the sexual activities and are secreted by males and females separately.

Functions of sex hormones are given below separately:

Male sex hormone: It is also called testosterone. It is secreted by testes and causes changes in secondary sexual character of boys like growth of facial hair like moustache, beard, etc. It also stimulates spermatogenesis.

Female sex hormone: It is also called estrogen. It is secreted by ovaries and controls the secondary sexual characters in females, appearance of mammary glands, etc. It also maintains pregnancy.

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.

Answer 7:

• (a) (ii) proper diet is needed for the rapid growth taking place in their body.
• (b) (i) menstruation starts.
• (c) (ii) chapati, dal, vegetables.

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

Answer 8: (a) Adam’s apple: The larynx or voice box in males begins to grow at puberty. . Boys develop larger voice boxes than girls so boys will have a deep voice. In males, the growing voice box may be seen as a protruding part of the throat which is called Adam’s apple.

(b) Secondary sexual characters: Features which help in distinguishing a man from a woman are called secondary sexual characters. In males, the secondary sexual characters are growth of hair on face, chest, under arms and pubic region. In females, the development of breasts and growth of hair in the under arm and pubic regions are the secondary sexual characters.

(c) Sex determination in the unborn baby is a process that begins at conception. The sex of the baby is determined by the chromosomes inherited from the parents. Humans have 23 pairs of chromosomes, with one pair being the sex chromosomes. Females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY). At fertilization, the sperm from the father contributes either an X or a Y chromosome, while the egg from the mother always contributes an X chromosome. If the sperm carries an X chromosome, the resulting combination will be XX, and the baby will be female. If the sperm carries a Y chromosome, the combination will be XY, and the baby will be male.

Question 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 thyroxine
3. Another term for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence

Answer 9:

Across

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

Down

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

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

Answer 10: From the above graph, we conclude that initially boys grow faster than girls from 0-8 years, and girls grow faster than boys from 8-16 years. But both reach their maximum height at the age of 20. Here boys show a greater increase in height than girls.