Reaching the Age of Adolescence - Exemplar Solutions 4

CBSE Class 8 Science
NCERT Exemplar Solutions
CHAPTER 10
Reaching the age of Adolescence

LONG ANSWER QUESTIONS

19. During adolescence, the body of boys and girls undergoes certain changes. Given below are a few of those changes.

(a) Broad shoulders

(b) Wider chests

(d) Development of muscles

(e) Development of mammary glands

(f) Growth of facial hair

(g) Acne and pimples on face

(h) Development of sex organs

(i) High-pitched voice

(j) Growth of pubic hair.

Categorise these changes into those that occur in boys and those that occur in girls and fill in the table given below.

Body changes during Adolescence
Boys	Girls

Ans: The given changes have been categorised as follows:-

Body changes during Adolescence
Boys	Girls
Broad shoulders	Wider region below waist
Wider chests	Development of mammary glands
Growth of muscles	Acne and pimples on face
Growth of facial hair	Development of sex organs
Acne and pimples on face	High-pitched voice
Development of sex organs	Development of pubic hair
Development of pubic hair

20. In Fig.10.2 mark the positions of the endocrine glands which release the hormones that:

(a) Controls the release of sex hormones.

(b) Is responsible for the secondary sexual characters in boys.

(d) Maintains the correct salt balance in the blood.

Ans: The position of the endocrine glands have been marked in the figure:

21. Given below are certain food items required for proper nourishment of adolescents. Name the nutrients present in the food items and write their functions.

Ans: The nutrients present in the food items and their functions are as follows:

22. Name the hormone which would be released during the following situations:

(a) A frightened person.

(b) Growth of a child to adult.

(d) Development of tadpole to frog.

Ans: a) Adrenaline (b) Growth hormone (c) Insect hormones (d) Thyroxine

23. In human females, each time during menstruation and release of egg, the inner wall of uterus thickens. Is this thickening permanent? Give reasons.

Ans. No, this thickening of the uterine wall is not permanent.

If the egg gets fertilised, it starts developing and gets embedded in the uterine wall resulting in pregnancy. During pregnancy, no more eggs are released and the thickened lining of the uterus is discharged only when the baby is born.

However, if fertilisation does not occur, the released egg and the thickened lining are shed off resulting in menstruation.

24. John and Radha were classmates since childhood. When Radha became eleven years old, she developed a little swelling on her neck. She visited the doctor who started medication for her. After a few years, John also developed a slight protrusion on his throat. He got worried and went to the doctor. But, the doctor assured him that it was a normal feature in boys while they are growing up. Can you think of any reasons for the difference in diagnoses?

Ans: The swelling on the neck of Radha may have been because of goiter, a condition of the thyroid gland during which the gland produces insufficient quantity of thyroxine. However, the protrusion in John’s throat would be Adam’s apple, a result of growth of voice box in adolescent boys.

25. Observe the chart and graph given in Fig. 10.3 carefully and answer the following questions.

(a) Which of the line represents the height of boys?

(b) Which line represents the height of girls?

(d) Is this pattern true for each individual?

Ans: (a) The red line (marked with small squares) represents the height of boys.

(b) The blue line (marked with small triangles) represents the height of girls.

(c) Pattern of increase in height: At the onset of puberty, girls grow faster in height than the boys and by the age of 18 years, approximately both reach their maximum height.

(d) No, the rate of growth in height varies among individuals. Some individuals may grow in height suddenly at puberty and then slow down, while others may grow gradually.

26. Salma had a very soft and smooth skin during her childhood. As she entered adolescence, she developed pimples on her face. The skin specialist advised her to wash her face at regular intervals. Can you explain the reasons for the appearance of pimples on her face and suggest ways to prevent them?

Ans: During adolescence, the secretions of sweat glands and sebaceous glands increases leading to the formation of acne and pimples. Wash the face regularly keeps the face clean and dry and helps to reduce the pimples.

27. Our government has legalised the age for marriage in boys and girls. Give reasons as to why one should get married after a certain age.

Ans: In our country, the legal age for marriage is 18 years for girls and 21 years for boys. This is because teenage mothers are not prepared mentally or physically for motherhood. Early marriage and motherhood causes health problems in both mother and the child. It also curtails employment opportunities for the young woman and may cause mental agony as she is not ready to shoulder responsibilities of motherhood. Also, the boys before that age may not be mentally matured and financially secure enough to take on the responsibilities of a family.

28. It is believed that height of a child depends upon the genes inherited from parents. However, it is often seen that tall parents may have short children and vice-versa. Are there factors other than genes, that can cause these variations?

Ans: The height of a child depends on the genes inherited from the parents but factors other than genes can also cause variations. It is important that children eat the right kind of food (balanced diet) during the growing years. A balanced diet helps the bones, muscles and other parts of the body to get adequate nourishment for growth, development and repair. Lack of a proper diet may lead to improper growth and the child may suffer from some kind of deformity.