Reaching the Age of Adolescence Class 8 Important Questions and Answers

Important questions of Class 8 Science Chapter 10 Reaching the Age of Adolescence is given below. These important questions will help students while preparing for the exam.  Practising these important questions will analyse their performance and work on their weak points. Score well in exam of Class 8 Science by going through these important questions. Students of Class 8 can download important questions of Class 8 Science Chapter 10 Reaching the Age of Adolescence PDF by clicking the link provided below.

Important Questions of Class 8 Science Chapter 10 Reaching the Age of Adolescence

Here you can get Class 8 Important Questions Science based on NCERT Text book for Class 8. Science Class 8 Important Questions are very helpful to score high marks in board exams. Here we have covered Important Questions on Reaching the Age of Adolescence for Class 8 Science subject.

Very Short Answer Questions

1. When does the growth start in human?
Answer:
 Growth begins from the day the child is born.

2. When do sudden and noticeable changes begin in human?
Answer:
 The sudden and noticeable changes begin in human in adolescence age.

3. What do the changes in the body of a child indicate?
Answer: 
The changes in the body of a child indicate that a child is on the way to become an adult.

4. What is the age of adolescence in human?
Answer:
 The age between 11 to 18 or 19 years is called the age of adolescence.

5. What is puberty?
Answer:
 The age at which boys and girls become capable of reproduction.

6. What changes occur during puberty?
Answer:
 At the time of puberty the bones of the arms and the legs elongate and make a person tall.

7. Do both boys and girls grow at the same rate?
Answer:
 No, girl grows faster than boys.

8. Do all the parts of the body grow at the same rate?
Answer:
 No, all the parts of the body do not grow at the same rate.

9. Which organ is called voice box?
Answer:
 Larynx.

10. What is Adam’s apple?
Answer: 
The protruding part of the throat in boys is called Adam’s apple.

11. Name main male and female reproductive organs.
Answer: 
Testes are the main male reproductive organs and ovaries are the main female reproductive organs.

12. What are hormones?
Answer: 
Hormones are the chemical substances which are produced by endocrine glands.

13. Name the male hormone.
Answer:
 Testosterone.

14. Name the female hormone.
Answer:
 Estrogen.

15. What is the name of the endocrine gland which controls the production of these male and female hormones?
Answer:
 Pituitary gland.

16. What is the puberty age in females?
Answer:
10 to 12 years.

17. What do you mean by menarche?
Answer:
 The first menstrual flow indicates menarche.

18. What is menopause?
Answer: 
Stoppage of menstruation is called menopause.

19. What are chromosomes?
Answer:
 The thread like structures in the nucleus are called chromosomes.

20. How many chromosomes are there in human cell?
Answer: 
There are 23 pairs of chromosomes in the nucleus of human cell.

21. What are sex chromosomes?
Answer:
 Out of 23 pairs, one pair of chromosomes is called sex chromosomes.

22. What are the name of these sex chromosomes?
Answer: 
Sex chromosomes are named as X and Y.

23. What are the chromosomes in female and male?
Answer: 
A female has two X chromosomes while a male has one X and one Y chromosomes.

24. What types of chromosomes occur in egg (female gamete)?
Answer:
 The egg always has one X chromosome.

25. What types of chromosomes occur in sperms?
Answer:
 Sperm has only X chromosome or only Y chromosome.

26. How many types of sperms are there?
Answer:
 Sperms are of two types: (i) One kind has X chromosomes. (ii) Other kind has Y chromosomes.

27. Who is responsible for sex determination of a child—mother or father?
Answer:
 The sex chromosomes of father determine the sex of an unborn baby.

28. Name some endocrine glands other than pituitary gland.
Answer:
 Some endocrine glands are thyroid, pancreas and adrenals.

29. Name the hormone produced by thyroid gland.
Answer:
 Thyroxine.

30. What is the name of hormone produced by pancreas?
Answer:
 Insulin is the hormone produced by pancreas.

31. Name the disease caused by less or not secretion of thyroxine hormone by thyroid.
Answer: 
Goitre.

32. Name the disease caused by less secretion of insulin hormone by the pancreas.
Answer:
 Diabetes.

33. What is the name of hormone produced by adrenal gland?
Answer:
 Adrenalin.

34. What is the function of adrenalin hormones?
Answer:
 Adrenalin hormone maintains the correct balance of salts in the blood.

35. Name the hormone which is necessary for the normal growth of a person.
Answer:
 Growth hormone.

36. Which endocrine gland produces the growth hormone?
Answer:
Pituitary gland.

37. What do you mean by metamorphosis?
Answer:
 The changes from larva to an adult is called metamorphosis. 

38. Name the hormone which controls metamorphosis in frog.
Answer:
 Thyroxine hormone which is produced by thyroid controls the metamorphosis in frogs.

39. Name the element which is essential to produce thyroxine hormone.
Answer:
 Iodine.

40. What happens if there is no iodine present in water?
Answer:
 If there is no iodine present in water, the tadpole cannot become adult.

41. What do you mean by health?
Answer:
 The physical and mental well being of a person is called health.

42. How can we keep our body healthy?
Answer:
 To keep the body healthy everyone needs to have a balanced diet.

43. What do you understand about the balance diet?
Answer:
 The food containing proteins, carbohydrate, fats and vitamins in requisite proportions is called balanced diet.

44. Why does mother’s milk is considered a better diet for infants?
Answer:
 Mother’s milk provides all the nutrients that they need. So mother’s milk is better food for infants.

45. What is the function of iron?
Answer:
 Iron helps to make the blood (haemoglobin in blood).

46. Name some iron rich food items.
Answer:
 Leafy vegetables, jaggery, meat and citrus fruits are rich in iron.

47. What do you mean by personal hygiene?
Answer:
 To keep themselves neat and clean by washing of clothes and by bathing is called personal hygiene.

48. What happens if cleanliness is not maintained?
Answer:
 If cleanliness is not maintained then there are chances of catching bacterial infection.

49. Name the causative organisms of AIDS.
Answer:
 It is a virus called HIV.

50. What is the legal age for marriage for girls and boys?
Answer:
 Legal age for marriage is 18 years for girls and 21 years for boys.

Short Answer Type Questions

1: What is the relation between adolescence and puberty?

Answer: Adolescence is the period of life when a body undergoes changes leading to reproductive maturity. These changes mark the onset of puberty.

2: Define the following:
a. Adolescence
b. Puberty

Answer:  (a) Adolescence: Human beings become capable of reproduction after the puberty sets in. The period of life when the body undergoes changes, leading to reproductive maturity, is called adolescence. Between the age of 11 years and 19 years children are called adolescents.

(b) Puberty: Puberty is the process of physical changes by which a child’s body matures into an adult body and it becomes capable of sexual reproduction to enable fertilisation. The human body undergo several changes during adolescence; these changes mark the onset of puberty

3: Define the following:
a. Adam’s apple
b. Secondary sexual characters

Answer: (a) Adam’s apple: In boys, at puberty, there develop a larger voice box which can be seen as a protruding part of the throat called Adam’s apple. Sometimes the muscles of the growing voice box go out of control and the voice becomes hoarse.

(b) Secondary sexual characters: During puberty many features develops in boys and girls that help to distinguish male from female, which is called secondary sexual character. This causes changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region, this causes changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region.

4: Write short notes on increase in height during puberty.

Answer: There is sudden increase in height during puberty, at this time the bones of arms and legs elongate and make a person tall.

5: Write short notes on changes in body shape during puberty.

Answer: There is change in body shape during puberty which includes broader shoulder and wider chests in boys and in girls region below the waist becomes wider.

6: Write short notes on voice change at puberty.

Answer: In boys, at puberty, there develop a larger voice box which can be seen as a protruding part of the throat called Adam’s apple. Sometimes the muscles of the growing voice box go out of control and the voice becomes hoarse.

7: What are the effects of increased activity of sweat and sebaceous glands? 

Answer: The increased secretion of sweat and sebaceous gland in the skin causes acne and pimples on the face of young people.

8: Write short notes on development of sex organs at puberty. 

Answer: At puberty male sex organs like testes and penis develop completely, the testes also begin to produce sperms, in the girls ovaries enlarge and starts releasing mature eggs, these are mainly controlled by hormones like testosterone in male and estrogen in female.

9: Define secondary sexual characters.

Answer: During puberty many features develops in boys and girls that help to distinguish male from female, which is called secondary sexual character. This causes changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region, this causes changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region.

10: Why changes in the body occur at adolescence?

Answer: The changes occurring in body at adolescence is mainly controlled by the action of hormones, Hormones are chemical substance secreted by endocrine gland that reaches to a particular body part via bloodstream. Changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region are all because of release of male hormone testosterone and changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region are all because of the female hormone estrogen produced by ovaries.

11: Write short notes on role of hormones in adolescence.

Answer: The changes occurring in body at adolescence is mainly controlled by the action of hormones, Hormones are chemical substance secreted by endocrine gland that reaches to a particular body part via bloodstream. Changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region are all because of release of male hormone testosterone and changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region are all because of the female hormone estrogen produced by ovaries.

12: The onset of puberty is controlled by hormones. Justify this statement.

Answer:  Hormones from endocrine glands like testes and ovaries stimulates testosterone in male and estrogen in female respectively . These hormones are released in bloodstream and they reaches to their target sites that is the particular body parts where they have to show their effects, the target sites respond to the hormone and it stimulate to the changes in the body at onset of puberty. Thus we can say that the onset of puberty is controlled by hormones.

13: Define menstruation, menarche and menopause.

Answer: Testosterone is the male hormone and estrogen is the female hormone. The uterine wall in females prepares itself to receive the developing fertilised egg. In case if there is no fertilisation, the thickened lining of uterine wall breaks down and goes out of body along with blood, this is called menstruation. Menarche is the first menstrual flow which begins at puberty and stoppage of menstruation is called as menopause.

14: How the sex of the unborn baby is determined? 

Answer: Female has two X chromosome while male has one X and one Y chromosome. The unfertilised egg has only one X chromosome but sperm are of two kinds one has X chromosome and other has Y chromosome, when sperm containing X chromosome fertilises with egg the zygote would have two X chromosomes and develop into female, similarly when sperm containing Y chromosome fertilises with egg the zygote would have one X and one Y chromosomes and develop into a male child.

15: Name some important hormones and disorders associated with those hormones in human body.
Answer: 
Under secretion of Insulin causes diabetes, thyroxine under secretion causes goitre.

16: Explain the function of pituitary gland. 

Answer: The production of all hormones is under the control of pituitary gland.The pituitary gland is termed the “Master Gland” because it directs other organs and endocrine glands, such as the adrenal glands and thyroid glands to suppress or induce hormone production, it involves following functions

  • Growth Hormone Production
  • Production of Hormones That Act on Other Endocrine Glands
  • Production of Hormones That Act on the Muscles and the Kidneys
  • Endocrine Function Regulation
  • Storage of Hormones Produced by the Hypothalamus

17: Explain the role of hormones in completing the life cycle of frogs and insects.

Answer: The life cycle of insects involves four different stage namely, egg, larva, pupa and adult. The changes from larva to adult is called metamorphosis, in insects metamorphosis is controlled by insects hormones in the same way in frog tadpole became a frog under the action of thyroxine hormone produced by thyroid.

18: Why it is important for an adolescence to have balanced diet?

Answer: Adolescence is the phase of growth and development of different body parts, thus it requires a complete healthy food that is the balanced diet.

19: Why it is important for an adolescence to have physical exercise?

Answer: Walking and playing in fresh air keeps the body fit and healthy. All youngsters should take walks, exercise and play outdoor games to keep themselves fit and for the proper growth and development of body.

20: How we can maintain physical and personal hygiene.

Answer: Take bath regularly, wash and clean all body parts every day. Use clean towel to wipe yourself, females should take special care of cleanliness during menstrual flow.

21: What is the cause of diabetes in human beings?

Answer: The under secretion of insulin hormone by pancreas leads to increase in blood glucose level and causes diabetes in human beings.

22: What is the cause of goitre in human beings?

Answer: The under secretion of thyroxine hormone by thyroid gland causes swelling of thyroid gland which causes swelling of the neck or larynx which is called as goitre.

23: What are the causes of AIDS?

Answer: AIDS is caused by a dangerous virus called HIV , this virus can pass on to a normal person from an infected person by Infected blood, Infected needles, multiple partners, Infected mother to her baby before birth, Injectable Drug Abuse.

24. What is adolescence?

Answer: Growing up is a natural process. The period of life, when the body undergoes changes, leading to reproductive maturity is called adolescence.

25. Why is adolescence also called teenage?

Answer: Adolescence begins around the age of 11 and lasts up to 18 or 19 years of age. Since this period covers the teens (13 to 18 or 19 years of age) adolescence is also called teenage.

26. What is the most important change which marks puberty?

Answer: 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.

27. Write the factors which affect the height of a person.

Answer: There are following two factors which affect the height:
(a) Genes inherited: The height of an individual is more or less similar to that of his or her parents. The height depends on the genes inherited by the parents.
(b) Height also depends on the diet taken by the person in this growing period.

28. What are the changes in shape of the body of girls and boys during adolescence?

Answer: In boys, the shoulders become broader and chests become wider in the age of adolescence. In girls the region below the waist becomes wider.
In boys the muscles of the body grow more prominently than in the girls. The changes occurring in adolescent boys and girls are different.

29. Explain the development of sex organs in male and female.

Answer: At the puberty, male sex organs like testes and penis develop completely. The testes also begin to produce sperms. In girls, the ovaries enlarge and eggs begin to mature. Ovaries also start releasing mature eggs. 

30. Some boys and girls have unproportionate body parts during adolescence. Why?

Answer: Sometimes boys and girls have unproportionate body parts. They look tall but face looks smaller. This is because all body parts do not grow at the same rate. But slowly they all catch up and body becomes balanced.

31. Explain the changes that occur in the voice of boys and girls during puberty.

Answer: The voice box or larynx begins to grow. The growing voice box in boys can be seen as a protruding part of the throat, called Adam’s apple. In girls the larynx is hardly visible from the outside because of its small size. Girls have high pitched voice, whereas boys have a deep voice.

32. Why some young people get acne and pimples on the face during puberty?

Answer: During puberty, the secretions from sweat glands and sebaceous glands increase. Many young people get acne and pimples on the face at this time because activity of these glands in the skin increase.

33. What are the secondary sexual characters in girls?

Answer: In girls, breasts begin to develop at the time of puberty. These features help us to distinguish the male from the female. These characters are called secondary sexual characters. Hair grows under the arms and in the region above the thighs or the pubic regions in girls.

34. Write some secondary sexual characters in boys.

Answer: The facial hair begin to grow in boys, that is moustaches and beard. Boys also develop hair on their chest. Hair grows under the arms and in the region above thighs or pubic region in boys like the girls.

35. What is the cause of the changes in human body during puberty?

Answer: The changes which occur during puberty are controlled by hormones. The hormones are the chemical substances. These are secretions from endocrine glands or endocrine system. These hormones are secreted from ovary, testes or pituitary gland at the time of puberty. The hormones secreted by pituitary stimulate testes and ovaries to secrete male and female hormones respectively.

36. How do hormones work?

Answer: Hormones are released by endocrine glands into blood stream to reach a particular body part called target site. The target site responds to the hormone. There are many endocrine glands or ductless glands in the body.

37. How do sex hormones work in the human body?

Answer: In girls, estrogen causes the development of mammary glands. They develop inside the breast and cause enlargement of breasts. In boys testosterone is secreted by testes and it causes growth of moustaches and beard.

38. Explain the term menstruation.

Answer: At the time of maturation the eggs are released by these ovaries. One egg is released at a time. If this egg is not fertilized, the released egg and thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in women which is called menstruation. Menstruation occurs once in about 28 to 30 days.

39. Explain menarche and menopause.

Answer: Menarche: The first menstrual flow beginning at puberty is termed as menarche.
Menopause: At 45 to 50 years of age the menstrual cycle stops. Stoppage of menstruation is termed as menopause.

40. What happens when egg is fertilized?

Answer: In case the egg is fertilized it begins to divide and then gets embedded in the uterus for further development. At last the fertilized egg is developed into a foetus.

41. Why pituitary gland is called master gland?

Answer: Pituitary gland is called master gland. It is the most important endocrine gland. The hormones secreted by the pituitary gland stimulate testes and ovaries to produce their hormones. Pituitary gland also controls the secretions of other endocrine glands. It is attached to the brain.

42. How do hormones help in the completion of life history of insects and frogs?

Answer: The changes from larva to adult is called metamorphosis. Metamorphosis in insects is controlled by insect hormones. In a frog it is controlled by thyroxine, the hormone produced by thyroid. Thyroxine production required the presence of iodine in water. If the water in which the tadpoles are growing does not contain sufficient iodine, the tadpoles cannot become adults.

43. Name the virus that causes AIDS. What are the medium through which this virus is transmitted?

Answer: AIDS is caused by a virus named HIV. It can be transmitted from an infected person to a healthy person by following ways:
(i) By infected syringes.
(ii) By infected mother to an infant.
(iii) By sexual contact with infected person.

44. Write some myths which are not facts.

Answer: The myths which are not facts:
(i) A girl becomes pregnant if she looks at a boy during menstruation.
(ii) The mother is responsible for the sex of her child.
(iii) A girl should not be allowed to work in the kitchen during menstruation.

Long Answer Type Questions

1: Adolescence is also a period of change in a person’s way of thinking. Justify the statement.  

Answer: Adolescence are more independent than before and are also self-conscious, during adolescence intellectual development take place and teenagers tend to spend considerable time in thinking, infact it the time when brain has the greatest capacity of learning. Sometimes adolescent may feel more attraction towards opposite sex because of release of sex hormones and they may also feel insecure while trying to adjust to the changes in mind and body, but they should understand that these changes are natural part of growing up.

2: Explain changes occurring in human body at puberty.

Answer: 
1. There is sudden increase in height during puberty, at this time the bones of arms and legs elongate and make a person tall.
2. There is change in body shape during puberty which includes broader shoulder and wider chests in boys and in girls region below the waist becomes wider.
3. In boys, at puberty, there develop a larger voice box which can be seen as a protruding part of the throat called Adam’s apple. Sometimes the muscles of the growing voice box go out of control and the voice becomes hoarse.
4. The increased secretion of sweat and sebaceous gland in the skin causes acne and pimples on the face of young people.
5. At puberty male sex organs like testes and penis develop completely, the testes also begin to produce sperms, in the girls ovaries enlarge and starts releasing mature eggs, these are mainly controlled by hormones like testosterone in male and estrogen in female.

6. During puberty many features develops in boys and girls that help to distinguish male from female, which is called secondary sexual character. This causes changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region, this causes changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region.

3: Explain secondary sexual characters and roles of hormones in initiating reproductive function

Answer: During puberty many features develops in boys and girls that help to distinguish male from female, which is called secondary sexual character. This causes changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region, this causes changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region.

The changes occuring in body at adolescence is mainly controlled by the action of hormones. Hormones are chemical substance secreted by endocrine gland that reaches to a particular body part via bloodstream. Changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region are all because of release of male hormone testosterone and changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region are all because of the female hormone estrogen produced by ovaries.

Hormones from endocrine glands like testes and ovaries stimulates testosterone in male and estrogen in female respectively .These hormones are released in bloodstream and they reaches to their target sites that is the particular body parts where they have to show their effects, the target sites respond to the hormone and it stimulate to the changes in the body at onset of puberty. Thus we can say that the onset of puberty is controlled by hormones.

4: How do hormones work? Explain with the help of a flow chart.
Answer:

Class 8 Science Chapter 10 Reaching the Age of Adolescence Important Question 1

5: Explain the sex determination of a baby in human.

Answer: Inside the fertilised egg or zygote is the instructor for determination of sex of the baby. The instruction is present in the chromosomes in the fertilised egg. All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these chromosomes two chromosomes are the sex chromosomes named X and Y. A female has two X chromosomes while a male has one X and one Y chromosomes. The eggs and sperms have only one set of chromosomes. The unfertilised egg always has one X chromosome.  But sperms are of two kinds. One kind has an X chromosome and other kind has Y chromosome. When a sperm containing X chromosome fertilises the eggs the zygote develops into a female child. If sperm contributes a Y chromosome to the egg at fertilisation, the zygote develops into a male child.

Class 8 Science Chapter 10 Reaching the Age of Adolescence Important Question 2

6: What are endocrine glands? Write the names of hormones and the functions of thyroid, pancreas and adrenal glands.

Answer: The glands which have no any duct to pour their secretions (hormones) into blood directly are called endocrine glands.
Thyroid: Thyroid is the endocrine gland. It secretes thyroxine hormone. If thyroid does not produce thyroxine, then thyroid glands increase in size and cause a disease called goitre.
Pancreas: Pancreas is also an endocrine gland which produces insulin hormone. If insulin is not produced sufficient then a person suffers from a disease called diabetes.
Adrenal: The hormone produced by adrenal gland is called adrenalin. This hormone maintains the correct salt balance in the blood. It also adjusts the body to stress when one is very angry, embarrassed or worried.

7: What do you mean by health? What are the factors which help to keep a good health?

Answer: The physical and mental well being of an individual is regarded as health.
The factors that help to keep a good health:
(i) One should take a balanced diet.
(ii) One should care and keep personal hygiene.
(iii) Walking and playing in fresh air keeps the body fit and healthy.
(iv) All young boys and girls should take walks, exercise and play outdoor games to keep good health.
(v) Avoid the alcohol and tobacco.
(vi) Drink clean water, breathe in clean air and eat clean food.

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