NCERT Exemplar Solution Class 8 Science Chapter 10
NCERT Exemplar Solution Class 8 Science Chapter 10 Reaching the Age of Adolescence all Questions Answer Solution. NCERT Exemplar Class 8 Science Chapter 10 Solution PDF.
NCERT Exemplar Solution Class 8 Science Chapter 10: Overview
NCERT Exemplar Solution Class 8 Science Chapter 10 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
8 |
Subject |
Science |
Chapter |
10 |
Chapter Name |
Reaching the Age of Adolescence |
NCERT Exemplar Solution Class 8 Science Chapter 10 Reaching the Age of Adolescence
Multiple Choice Questions
1) 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 mother.
c) Gets one sex chromosome from the mother and the other from the father.
d) Gets sex chromosome only from the father.
Answer:- c) Gets one sex chromosome from the mother and the other from the father.
No. Only mother is not responsible for the sex determination of the child. Child gets one Chromosome from mother and one from father and thus the sex of child is determined.
2) AIDS can spread from an infected person to another person through
a) Sharing food
b) Blood transfusion
c) Sharing comb
d) A mosquito bite
Answer:- b) Blood transfusion
AIDS can be spread from an infected person to another person through blood transfusion. By sharing needles and syringes. An infected mother can transfer it to child through milk.
3) Given below are events that lead to pregnancy and development of embryo.
i) Fertilisation of egg
ii) maturation of egg
iii) Release of egg
iv) embedding of embryo in 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
Answer:- d) II, III, I, IV
The correct sequence of pregnancy and development of embryo is maturation of egg, release of egg , Fertilisation of egg and further formation of zygote and then into embryo. These embryo is embedded on the thickened wall of uterus.
4) For the metamorphosis of tadpole which of the following elements must be available in water?
a) Chlorine
b) Carbon
c) Sulphur
d) Iodine
Answer;- d) Iodine
Metamorphosis is the sudden change from larva to adult frog. It is controlled by the Thyroxine, which is the hormone produced by the thyroid gland. These Thyroxine require the sufficient Iodine in the water.
5) 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.
Answer:- b) Increase in height
The suddenly increase in the height of the boys at the onset of puberty is a visible change. These time bones of legs and arms are elongate and increase the height.
6) 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
Answer:- d) chromosome
Genes are responsible for the sex determination of the baby. These genes are present in the Chromosomes which is present in Nucleus.
Very short Answer Questions
7) Unscramble the underlined words in the following sentences.
a) Reproductive life of a woman lasts from hacreemn to spauoemen.
Answer:- Reproduction life of a woman lasts from menarche to menopause.
b) The development of a caterpillar to an adult butterfly is termed as poommertaissh.
Answer:- The development of a caterpillar to an adult butterfly is termed as metamorphosis.
c) The overgrowth of sumselc in xalnyrleads to the hoarse voice in adolescent boys.
Answer:- The overgrowth of muscles in larynx leads to the hoarse voice in adolescent boys.
d) Dannalier helps the body to adjust and fight the stress.
Answer:- Adrenalin helps the body to adjust and fight the stress.
8) Complete the following sentences.
a) In females, the uterine wall thickens to receive the _________.
Answer:- In females the uterine wall thickens to receive the fertilised egg.
b) Endocrine glands release hormones directly into _________ for transportation to the ___________.
Answer:- Endocrine glands release hormones directly into blood stream for transportation to the target site.
c) The sex hormones, _____________ and estrogen are responsible for the development of ____________ characters.
Answer:- The sex hormones, Testosterone and estrogen are responsible for the development of secondary sexual characters.
d) Release of sex hormones is under the control of a hormone secreted from the _____________.
Answer:- Release of sex hormones is under the control of a hormone secreted from the pituitary gland.
9) Give a suitable word for each of the following statements.
a) The site which responds to a hormone.
Answer:- Target site
b) Name of a gland which transports secretions through ducts.
Answer:- sweat glands and salivary gland
c) Chemicals which control changes at adolescence stage.
Answer:- Hormones
d) It marks the beginning of reproductive period.
Answer:- puberty.
10) Name the hormone that is released by testis at the onset of puberty.
Answer:-Testosterone is the hormone released By male testis at the onset of puberty.
11) Name the female hormone produced by ovaries that helps in development of mammary glands.
Answer:- Estrogen is the hormone released by the female ovaries which helps in the development of mammary glands.
Short Answer Questions
12) Match the hormones given in Column A with their deficiency disease given in column B.
Column A
|
Column B |
a) Thyroxine | i) Salt imbalance |
b) Growth hormone | ii) Diabetes |
c) Insulin | iii) Goitre |
d) Adrenal hormone | iv) Dwarfism |
Answer:-
A) Thyroxine→ i) salt imbalance
B) Growth hormone→ iv) Dwarfism
C) Insulin → ii) Diabetes
D) Adrenal hormone → iii) Goitre
13) Lila always eats only dal and rise in every meal. She often falls ill and has become prone to diseases. Can you suggest changes in her diet which can make her healthy and free disease?
Answer:- she did not take a balanced diet. She only take adequate nutritional supplements in her meals. She contains only protein and carbohydrates in her every meal. But she don’t take any vitamins, minerals, fats and other nutrients in her meal. These all the nutrients will protect her from the disease and increase her immunity. Therefore my suggestion to lila would be to Take a complete balanced diet including fruits and vegetables in meals of every day.
14) Mention any two features each that are seen in boys and girls each to distinguish them from each other at puberty.
Answer:-
Two features seen in boys at puberty are –I) Growth of muscles.
II) Broad shoulders
III) Acne and pimples on face
IV) Development of sex organs
Two features seen in girls at puberty are-
I) Development of sex organs
II) Development of pubic hairs.
III) Development of mammary glands
IV) Region below the waist becomes wider.
V) High pitched voice.
15) We should avoid taking medicines / drug unless prescribed by a doctor. Give reasons.
Answer:-
Many drugs are addictive. These drugs if taken once got the habit of that. Which can harm the body for a longer time. They can spoil the health and happiness. High and heavy doses of medicines can harm the body and mind health. Therefore we should take drug as per doctor’s concern.
16) A few of paheli’s classmates eat potato chips and burgers regularly during the recess at school. Are they healthy eating habits? Give reasons.
Answer:- No. Eating chips and burgers regularly is not a healthy eating habits. These fried and fast-food contains so much oil and fats in it. These fats get stored in the body and makes body fatty. Also these chips and burgers does not contains more nutritional value.
17) Read the statements given below and fill up the blanks with the correct words listed in the box.
Deep, ductless, nutrients, thyroxine
a) The meal that includes all ____________ is a balanced diet.
Answer:- The meal that includes all Nutrients is a balanced diet.
b) Insufficient production of __________ in the tadpoles leads to their incomplete development.
Answer:- Insufficient production of Thyroxine in the tadpoles leads to their incomplete development.
c) Endocrine glands are also called ____________ glands.
Answer:- Endocrine glands are also called ductless glands.
d) After attending puberty boys develop a __________ voice.
Answer:- After attending puberty boys develop a high pitched deep voice.
18) Fill the blank circles in figure 10.1 and identify the sex of child A and B.
Fig. 10.1
Answer:-
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
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.
Categories 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
Answer:-
Body changes | |
Boys | Girls |
Growth of facial hair | Development of mammary glands |
Growth of muscle | Acne and pimples on face |
Acne and pimples on face
|
Development of pubic hair
|
Broad shoulders | High pitched voice |
Wider chests | Development of sex organs |
Development of sex organs | Wider region below waist |
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.
Answer:- pituitary gland
b) Is responsible for the secondary sexual characters in boys.
Answer:- ovaries in females and testis in males
c) Prevents diabetes.
Answer:- pancreas
d) Maintains the correct salt balance in the blood.
Answer:- thyroid gland
Answer:-
21) Given below are certain food items required for proper nourishment of adolescent. Name the nutrients present in the food items and write their functions.
Sr. No | Food items
|
Major
Nutrient |
Functions |
1.
|
Pulses and nuts | ||
2. |
Oranges and amla | ||
3. |
Sugar,
Roti |
||
4. |
Oils |
||
5. |
Vegetables |
|
Answer:-
Sr. No | Food items
|
Major
Nutrient |
Functions |
1.
|
Pulses and nuts | Proteins | Growth, repair of body cells |
2. |
Oranges and amla | Iron and vitamins | Formation of blood keeps the body healthy |
3. |
Sugar,
Roti |
Carbohydrates | Provide energy |
4. |
Oils |
Fats | Provide energy |
5. |
Vegetables |
Vitamins and minerals
|
Keeps the body healthy and disease free. |
22) Name the hormone which would be released during the following situations:
a) A frightened person.
Answer:- Adrenaline will be released when a person is frightened.
b) Growth of a child to adult.
Answer:- Growth hormone is important for growth of child to adult.
c) Development of caterpillar to moth.
Answer:- insect hormones is released for the development of caterpillar to moth.
d) Development of tadpole to frog.
Answer:- Thyroxine hormone is important for the growth of tadpole to frog.
23) In human females, each time during maturation and release of egg her inner wall of uterus thickness. Is this thickening permanent? Give reason.
Answer:-
No the thickening is not permanent. When the maturation of egg and it’s release takes place, the uterus slightly thick in size. These is because during the release of egg if the egg is fertilised, then the development of embryo takes place after embedded on the wall of uterus. The supply of all the nutrition is done from the wall of uterus. The thickened lining of uterus wall is discharged after the child is born. And if during the release of egg fertilisation does not occur then the thickened lining of the uterus wall shed off with the blood which we called as 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?
Answer:- these two conditions are not similar at all. During the puberty boys voice box or the larynx start to grow. These growing voice box results into a protrusion part . These is known as Adam’s apple. Due to which boys develop a larger voice box and deep voice.
But these condition is not occur in girls . Girls larynx is not seen from outside because it has small size.
But here radha got an little swelling on her neck these may be due to goitre . Therefore doctor start medication to her.
25) Observe the chart and graph given in fig. 10.3 carefully and answer the following questions.
Age in years | % of full height | |
Boys. Girls | ||
8
|
72% | 77% |
9
|
75% | 81% |
10
|
78% | 84% |
11
|
81% | 88% |
12
|
84% | 91% |
13
|
88% | 95% |
14
|
92% | 98% |
15
|
95% | 99% |
16
|
98% | 99.5% |
17
|
99% | 100% |
18
|
100% | 100% |
Fig. 10.3
a) Which of the line represents the height of boys ?
Answer:- The height of the boys is represented by the red line.
b) Which line represents the height of girls ?
Answer:- The height of girls is represented by the blue line.
c) What is the difference between the pattern of increase in the height of boys and girls?
Answer:- the difference between the pattern of increase in the height of boys and girls is, girls grow faster in heightin their puberty age than the boys. But at the age of 18 years, boys and girls both reaches their at their maximum height.
d) Is this pattern true for each individual?
Answer:- No. These pattern is not same for each person. The growth of height varies person to person. Some girls or boys suddenly grow in height at Their puberty. And after that their height don’t grow so much. But some children’s height grow slow and steady upto a certain age.
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 reasons for the appearance of pimples on her face and suggest ways to prevent them?
Answer:- Adolescence begin early in the girls. These stage is called as teenagers. On the onset of puberty some sudden changes may occur in the teenagers body. These also include the acne and pimples on the face. This is due to the increased secretion of sweat glands and sebaceous glands. Sebaceous glands are also known as oil glands. If the activity of these glands increase , acne and pimples appear on the face. For preventing these acne and pimples, we should take proper care of face. Washing face regularly will help to prevent it.
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.
Answer:- out country has the legalised age for marriage, 21 years for boys and 18 years for the girls. Early age motherhood is not good for the teenage mother. These can cause severe health problems to mother and child. During the pregnancy and delivery any one of them can be dead. These is the major risk during teenagers pregnancy. Early marriages of girls become responsible for unemployment. Many of them leave their education.
In boys also early marriages can cause problems because they are prepared for taking responsibility of the family and children. And also teenager boys are not prepared financially for it.
28) It is believed that height of a child depends upon the genes inherited from parents. However, it is a often seen that tall parents may have short children and vice- versa. Are these factors other than genes, that can cause these variations?
Answer:-
Yes. Some other factors other than genes are responsible for the growth of height. The genes are carriers of the information about height which is been inherited from the mother and father but after the birth also some factors effect on height. The proper diet and nutrition values in the meals affects the growth of height. At the time of puberty the release of hormones may affect it. Regular practice of exercise and stretches can positively affect the growth of height. Weak immune system and health problems or diseases can affect on the height as well.