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NCERT Solution for Class 8 Science Chapter 7 – Reaching The Age of Adolescence

Last Updated : 23 May, 2023
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NCERT Solution for Class 8 Science Chapter 7 Reaching The Age of Adolescence: The chapter on Reaching the Age of Adolescence is important for students approaching the board exams. This article introduces NCERT solutions designed to help students explain the concepts of further learning and how to write to get good grades on exams. The solutions are presented in very simple language for ease of understanding.

NCERT CBSE Chapter 7 Reaching The Age of Adolescence of Class 8 Science discusses the physical and emotional changes that occur during this stage of life, including the onset of puberty, changes in reproductive organs, secondary sexual characteristics, hormonal changes, and the importance of personal hygiene during adolescence. It also provides information on the challenges and concerns faced by adolescents and the importance of maintaining a healthy lifestyle during this period. Revise the basic concepts of Reaching the Age of Adolescence for quick revision and class notes.

Q1: What is the term used for Chemical Secretions of Endocrine Glands responsible for changes taking place in the body?

Answer:

Hormone is the term used for chemical secretions of endocrine glands. The changes which occur in adolescence are controlled by hormones.

Q2: Define Adolescence.

Answer:

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 up to 18 or 19 years of age.

Q3: What is Menstruation? Explain.

Answer:

In females, the reproductive phase of life begins at 10 to 12 years of age and generally lasts till the age of approximately 45 to 50 years. The ova begin to mature with the onset of puberty. One ovum matures and is released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. This results in pregnancy. If fertilization does not occur, the released egg and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in women which is called menstruation.

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

Answer:

The human body undergoes several changes during adolescence. These changes mark the onset of puberty:

  1. Boys and girls become capable of reproduction.
  2. A sudden increase in height.
  3. Broader shoulders in boys & wider waist in girls.
  4. The voice box or the larynx begins to grow in boys.
  5. Many young people get acne and pimples on the face at this time because of the increased activity of sweat & sebaceous glands in the skin.
  6. Male sex organs like the testes and penis develop completely. In girls, the ovaries enlarge and eggs begin to mature.
  7. Intellectual development takes place at puberty.
  8. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, mustaches and beards.
  9. Boys also develop hair on their chests. In both, boys and girls, hair grows under the arms and in the region above the thighs or the pubic region.

Q5: Prepare a Table having two columns depicting the names of Endocrine Glands and Hormones secreted by them.

Answer:

Endocrine Glands

Hormones Secreted

Testes

Testosterone

Ovary

Estrogen, Progesterone

Pituitary Gland

Growth Hormone, Prolactin, Thyroid Stimulating Hormone, Follicle Stimulating Hormone, Oxytocin, etc.

Thyroid Gland

Thyroxine

Adrenal Gland

Adrenaline

Pancreas

Insulin

Q6: What are Sex Hormones? Why are they named so? State their function.

Answer:

Hormones secreted by the testes and ovaries are called sex hormones. They are responsible for the male and female secondary sexual characteristics and hence are named sex hormones.

Q7. Choose the correct option.

  1. Adolescents should be careful about what they eat, because
    1. (i) Proper diet develops their brains.
    2. (ii) proper diet is needed for the rapid growth taking place in their body.
    3. (iii) adolescents feel hungry all the time.
    4. (iv) Taste buds are well-developed in teenagers.
  2. Reproductive age in women starts when their
    1. (i) menstruation starts.
    2. (ii) breasts start developing.
    3. (iii) body weight increases.
    4. (iv) height increases.
  3. The right meal for adolescents consists of
    1. (i) chips, noodles, and coke.
    2. (ii) chapati, dal, vegetables.
    3. (iii) rice, noodles, and burger.
    4. (iv) vegetable cutlets, chips, and lemon drink.

Answer:

  1. (ii) proper diet is needed for the rapid growth taking place in their body.
  2. (i) menstruation starts.
  3. (ii) chapati, dal, vegetables.

Q8: Write notes on:

  • (a) Adam’s apple.
  • (b) Secondary sexual characters.
  • (c) Sex determination in the unborn baby.

Answer:

a) Adam’s apple: An Adam’s apple is the protrusion on the front of a boy’s throat. It’s the cartilage that covers the front of the larynx or voice box. In girls, the larynx is hardly visible from the outside because of its small size.

b) Secondary sexual characters: At puberty, breasts begin to develop in girls and boys begin to grow facial hair, that is, moustaches and beard. Boys also develop hair on their chests. In both, boys and girls, hair grows under the arms and in the region above the thighs or the pubic region. As these features help to distinguish the male from the female they are called secondary sexual characters.

c) Sex determination in the unborn baby: Sex chromosomes play a crucial role in determining the sex of the unborn baby. Typically, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The father’s sperm carries either an X or a Y chromosome, while the mother’s egg always contributes an X chromosome. If the sperm carrying an X chromosome fertilizes the egg, the resulting combination (XX) will develop into a female baby. On the other hand, if the sperm carrying a Y chromosome fertilizes the egg, the combination (XY) will develop into a male baby.

Q9: 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 the 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 the bloodstream
  • 6. Voicebox
  • 7. Term for changes in adolescence
Q-9

 

Answer:

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
Q-9 Solution

 

Q10: The table below shows the data on the likely heights of boys and girls as they grow in age. Draw graphs showing the height and age of both boys and girls on the same graph paper. What conclusions can be drawn from these graphs?

Q-10

Answer:

The above graph explains the relation between the height of boys/girls with age. It can be observed that during the age of 4-8 years, girls have less height in comparison to boys. However, as soon as girls reach 12- 13 years (puberty), their rate of increase in height is more than that of boys. There is a sudden increase in height in both cases during puberty. Also, the growth in both sexes becomes stable in later ages.



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