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

Here you will find NCERT Solutions for Class 8 Science Chapter 10 Reaching the Age of Adolescence which will be useful in expanding student's horizon as it cover variety of questions. These NCERT Solutions for Class 8 are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics. In the examinations, you can come up with better answers and lay out the main point effectively.

NCERT Solutions is an effective method for learning since you can be le to learn a lot within a short time. You can pinpoint your weaknesses with the help of these NCERT Solutions for Class 8 Science and prepare accordingly to change it in a positive way. Chapter 10 Reaching the Age of Adolescence NCERT Questions and Answers will make entire memorizing process effortless and entertaining.

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


These Class 8 Science NCERT Solutions can be useful in improving the marks in the examinations and have edge over your classmates. You will understand the various factors through which one can improve their efficiency and eventually scores higher in the exam. Chapter 10 NCERT Questions and Answers can be used to enrich knowledge and make lessons for learners more exciting.

 Study Material for Class 8 Science Chapter 10 Reaching the Age of Adolescence

Page No: 124

Exercise

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

Answer

Hormones are chemical substances which are secreted by endocrine glands. They are responsible for changes taking place in the body.

2. Define adolescence.

Answer

Adolescence is the period of life, when the body undergoes changes, leading to reproductive maturity. It begins around the age of 11 and lasts till 18 or 19 years of age. The period of adolescence may vary from person to person.

3. What is menstruation? Explain.

Answer

Menstruation is the process of the shedding of the uterine lining on a regular monthly basis in woman. During menstruation the uterus wall along with blood vessels break off. This causes blood to come out and a new wall of uterus is formed. Menstruation lasts generally lasts for 4 to 5 days.

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

Answer

Changes at puberty:
→ Sudden increase in height and weight.
→ Broadening of shoulders and widening of chest in boys. In girls, the region below waist becomes wider.
→ In boys, under the influence of hormones, the larynx becomes prominent, the vocal cords become longer and thicker. These changes cause the voice to become hoarse.
→ Appearance of hair in areas such as underarms, face, hands, and legs.
→ Appearance of acne as a result of excessive secretion of oil from skin.
→ Testis grows and starts producing sperms in males, whereas in females, the ovary enlarges and starts producing matured eggs.

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

Answer

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

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

Answer

Sex hormones are the hormones that control the development of secondary sexual characteristics and also regulate the proper functioning of the sex organs. They are named so because they are produced in both males and females by the respective sex organs under the influence of the pituitary gland.
Functions of sex hormones:
→ Testosterone: This hormone brings about secondary sex characters in boys such as the growth of a beard, the voice becoming hoarse, development of reproductive organs, etc.
→ Oestrogen: This hormone is responsible for the development of secondary sexual characters in females such as the enlargement of breasts, development of female reproductive organs, etc.

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: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse.

(b) Secondary sexual characters: These are features features that help in distinguishing the male and the female body from each other. They are physical or behavioural characteristics that appear in humans at the time of puberty.
Secondary sexual characters in boys:
→ Appearance of moustache and beard.
→ Appearance of chest hair.
→ Growth of hair in genital area and other parts of the skin.
Secondary sexual character in girls:
→ Increase in breast size and darkening of the skin of nipples present at the tip of the breasts.
→ Growth of hair in genital area and other body parts.
→ Sex determination in the unborn baby.

(c) Sex determination in an unborn baby: Sex of a unborn baby depends upon the pair of sex chromosomes that are present in the cells of the baby. The two sex chromosomes are X and Y. The unfertilised egg always has one X chromosome.But sperms are of two kinds. One kind has an X chromosome, and the other kind has a Y chromosome.
If both the chromosmes are X then the baby is girl.
If one of the chromosomes are X and the other is Y then the baby is boy.

Page No: 125

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

Question No. 9

Answer

Answer No. 9
Across
3. ADAM'S APPLE
4. ENDOCRINE
7. PITUITARY
8. HORMONE
9. INSULIN
10. ESTROGEN

Down
1. TESTOSTERONE
2. THYROID
3. ADOLESCENCE
5. TARGET SITE
6. LARYNX
7. PUBERTY

Page No: 126

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

Question No 10 Graph

Answer

The graph depicts the relation between the age and height of both boys and girls. During puberty, there is a sudden increase in height of both boys and girls. On the basis of the above graph, it can be observed that during the age of 4-8 years, girls have less height as compared to boys. However, as soon as girls reach 12- 13 years, their height shows a sudden increase and becomes more than boys. In later years, growth in both sexes becomes stable. Growth during puberty is under the control of hormones.

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


These NCERT Solutions for Class 8 Science Chapter 10 are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics. It will make you aware of the all the topics and ensure consistency in the preparation level. Your marks play an important role in shaping future thus these NCERT Solutions will become your comprehensive guide in easy learning and evaluating yourself.

Class 8 Science Chapter 10 Reaching the Age of Adolescence NCERT Questions and Answers - Topics


• Adolescence and Puberty
• Changes at Puberty
→ Increase in Height
→ Change in Body Shape
→ Voice Change
→ Increased Activity of Sweat and Sebaceous Glands
→ Development of Sex Organs
→ Reaching Mental, Intellectual and Emotional Maturity
• Secondary Sexual Characters
• Role of Hormones in Initiating Reproductive Function
• Reproductive Phase of Life in Humans
• How is the Sex of the Baby Determined?
→ Boy or Girl?
• Hormones other than Sex Hormones
• Role of Hormones in Completing the Life History of Insects and Frogs
• Reproductive Health
→ Nutritional Needs of the Adolescents
→ Personal Hygiene
→ Physical exercise

Chapter 10 Reaching the Age of Adolescence NCERT Solutions for Class 8 Science  - Notes


• The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age.

• The human body undergoes several changes during adolescence. These changes mark the onset of puberty. The most important change which marks puberty is that boys and girls become capable of reproduction.

• The most conspicuous change during puberty is the sudden increase in height.

• In boys, the shoulders broaden and muscles of the body grow more prominently than in the girls.  For girls, there is widening of the region below the waist and less growth of muscle.

• During puberty, it is being noticed that the voice of boys starts cracking and their voice box or larynx starts to grow.

→ The increase in the size of voice box in boys is seen as a prominent protrusion in the neck. This protrusion is called Adam’s apple.

• During puberty, there is an increase in the secretion of sweat glands and sebaceous glands which may lead to the appearance of acne and pimples.

• At puberty, male sex organs like the testis and penis develop completely and begin to produce sperms.  In girls, the ovaries enlarge and start releasing eggs.

• During adolescence, a person’s brain has the greatest capacity for learning.

• Hormones are chemical substances secreted by the endocrine glands. Hormones control the changes during adolescence. The pituitary gland secretes hormones which in turn control the production of hormone from other endocrine glands.

• The male hormone or testosterone begins to be released by the testes. Once puberty is reached in girls, ovaries begin to produce the female hormone or estrogen which makes the breasts develop.

• In females, the reproductive phase of life begins at puberty (10 to 12 years of age) and generally lasts till the age of approximately 45 to 50 years.

• Ova mature and is released by one of the ovaries once in about 28-30 days. During this period, the uterus becomes thick so as to receive the mature ova. A fertilized egg develops pregnancy.

• Unfertilized egg along with the thickened lining of the uterus and blood vessels are shed off in the form of bleeding in women once in about 28-30 days is termed Menstruation.

• Initial menstrual flow begins at puberty and is termed Menarche.

• Stoppage of the menstrual cycle at 45-50 years of age is called Menopause.

• Instruction for determining the sex of a baby is present in the chromosome of the fertilized egg (zygote). Humans have 23 pairs of chromosomes, including two sex chromosomes (X and Y) in the nucleus of their cells.

• Females have two X chromosomes and males have one X and one Y chromosome. An unfertilized egg has one X chromosome. Sperm may have one X chromosome or Y chromosome. Therefore, the sex chromosomes of the father determine the sex of the unborn baby.

• To keep the body healthy, every human being, at any age, needs to have a balanced diet.

• Adolescence is a stage of rapid growth and development. So a balanced diet comprising proteins, carbohydrates, fats, minerals, and vitamins in requisite quantity is essential. 

• Iron builds blood. Iron-rich food such as leafy vegetables, jaggery, meat, citrus, Indian gooseberry is good for adolescents.

• Adolescents should take walk, exercise, and play outdoor games in fresh air to keep them fit and healthy.

Chapter 10 Reaching the Age of Adolescence Class 8 Science Questions and Answers - MCQ Questions with answers


1. Which of the following will occur in females at puberty?
a) Ovulation
b) Enlargement of breasts
c) Broadening of hips
d) All of the above
► d) All of the above

2. Which of the following statements is true?
a) Boys reach puberty at an earlier age than girls.
b) Girls reach puberty earlier than boys.
c) At the end of rapid growth, girls are normally heavier than boys.
d) Between the age of 4 to 12, girls grow faster than boys.
► b) Girls reach puberty earlier than boys.

3. Which gland is called dual gland?
a) Adrenaline
b) Liver
c) Lung
d) Testis
► d) Testis

4. The hormone which brings about characteristic changes in male at puberty is called
a) Testosterone
b) Androgen
c) FSH
d) Insulin
► a) Testosterone

5. An organ where a hormone shows its effect is called
a) Terminator
b) Initiator
c) Effectors
d) Target site
► d) Target site

6. Sebaceous gland is also known as
a) Pancreatic gland
b) Oil gland
c) Sweat gland
d) Mater gland
► b) Oil gland

7. Which one is another terms for teenage is
a) Maturity
b) Puberty
c) Adolescence
d) Thyroid
► c) Adolescence

8. The male hormone is
a) Estrogen
b) Progestron
c) Testosterone
d) All of the above
► c) Testosterone

9. The period of maturity of reproductive organs is called
a) Adolescence period
b) Menstruation
c) Gestation period
d) None of the above
► a) Adolescence period

10. Many people get acne and pimples on the face at puberty because of
a) Increased activity of sweat gland and oil gland
b) Only oil gland
c) Absence of growth hormones
d) Only sweat gland
► a) Increased activity of sweat gland and oil gland

Class 8 NCERT Solutions is an effective method for learning since you can be le to learn a lot within a short time. Students should also refer previous year questions and practise test papers and worksheets to assess their key areas. NCERT Solutions for Science prepared by our experts try to provide all round clarity of questions.

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