Ncert solutions science class 8 Solutions for Chapter 10 reaching the age of adolescence

The right meal for adolescents consists of

Adolescents should be careful about what they eat, because

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

Q1) What is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body?

The belief that the mother is completely responsible for the sex of the child is wrong because the child

(a) gets sex chromosome only from the mother.

(b) develops in the body of the mother.

(c) gets one sex chromosome from the mother and the other from the father.

(d) gets sex chromosome only from the father

Define adolescence.

AIDS can spread from an infected person to another person through

(a) sharing food

(b) blood transfusion

(c) sharing comb

(d) a mosquito bite

Q2) Define adolescence.

What is menstruation? Explain

Q3) What is menstruation? Explain.

Given below are events that lead to pregnancy and the development of an embryo.

i)Fertilization of egg

ii)Maturation of egg

iii)Release of egg

iv)Embedding of the embryo in the thickened uterine wall. Which of the following options gives the correct order of sequence in which they occur?

(a) i, ii, iii, iv,

(b) ii, i, iii, iv

(c) i, iv, ii, iii

(d) ii, iii, i, iv

Q4) List changes in the body that take place at puberty.

For the metamorphosis of tadpoles which of the following elements must be available in the water?

(a) chlorine

(b) carbon

(c) sulphur

(d) iodine

List changes in the body that take place at puberty

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

The most conspicuous visible change that occurs in boys during puberty is:

(a) development in voice box.

(b) increase in height.

(c) production of sperms.

(d) increased sweating.

Q5) Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.

What are sex hormones? Why are they named so? State their function

Q6) What are sex hormones? Why are they named so? State their function.

Structures present in a cell which is responsible for determination of the sex of a baby is

(a) cytoplasm

(b) cell membrane

(c) nucleus

(d) chromosome

Unscramble the underlined words in the following sentences.

(a) Reproductive life of a woman lasts from hacreemn to spauoemen.

(b) The development of a caterpillar to an adult butterfly is termed as poommertaissh.

(c) The overgrowth of sumselc in xalnyr leads to the hoarse voice in adolescent boys.

(d) Dannalier helps the body to adjust and fight the stress.

Q7) 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.

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.

Reproductive age in women starts when their

Complete the following sentences.

(a) In females, the uterine wall thickens to receive the __________.

(b) Endocrine glands release hormones directly into___for transportation to the __________.

(c) The sex hormones,___ and estrogen are responsible for the development of __________ characters.

(d) Release of sex hormones is under the control of a hormone secreted from the __________.

Q8) Write notes on—

(a) Adam’s apple.

(b) Secondary sexual characters.

(c) Sex determination in the unborn baby.

Write notes on—

(a) Adam’s apple.

(b) Secondary sexual characters.

(c) Sex determination in the unborn baby.

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

Q9) Word game : Use the clues to work out the words.

Across

1. Protruding voice box in boys
2. Glands without ducts
3. Endocrine gland attached to brain
4. Secretion of endocrine glands
5. Pancreatic hormone
6. Female hormone

Down

7. Male hormone
8. Secretes thyroxine
9. Another term for teenage
10. Hormone reaches here through blood stream
11. Voice box
12. Term for changes at adolescence

Give a suitable word for each of the following statements.

(a) The site which responds to a hormone.

(b) Name of a gland which transports secretions through ducts.

(c) Chemicals which control changes at the adolescence stage.

(d) It marks the beginning of reproductive period.

Q10) 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?

Name the hormone that is released by testes at the onset of puberty.

Name the female hormone produced by ovaries that helps in the development of mammary glands.

Match the hormones given in Column A with their deficiency disease given in Column B.

A few of Paheli’s classmates eat potato chips and burgers regularly during recess at school. Are they healthy eating habits? Give reasons.

Read the statements given below and fill up the blanks with the correct words listed in the box.

(a) The meal that includes all __________ is a balanced diet.

(b) Insufficient production of __________ in the tadpoles leads to their incomplete development.

(c) Endocrine glands are also called __________ glands.

(d) After attaining puberty boys develop a__ voice

Fill the blank circles in figure and identify the sex of child A and B.

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

(c) Wider region below waist

(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.

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

In Fig. 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.

(c) prevents diabetes.

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

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

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

(a) a frightened person.

(b) growth of a child to an adult.

(c) development of caterpillar to moth.

(d) development of tadpole to frog.

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

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?

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

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

(b) Which line represents the height of girls?

(c) What is the difference between the pattern of increase in the height of boys and girls?

(d) Is this pattern true for each individual?

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?

It is believed that the 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?

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.