Biology Question

Class 8 Chapter 15

Reaching the age of adolescence

A. Fill in the blanks.

1. Endocrine glands release hormones into the blood stream.

2. Larynx is also known as the voice box.

3. Acne and pimples are common in adolescence due to increased production of Sebum by the sebaceous glands.

4. Deficiency of Vitamin D reduces the absorption of calcium by the body.

5. Thyroxine hormone is essential for metamorphosis to happen in a frog.

6. Autosomes are chromosomes other than the sex chromosomes.

B. Match the following.

1. Ovary. – Progesterone

2. Pancreas – insulin

3. Adrenals – adrenaline

4. Testes – testosterone

5. Thyroid – thyroxine

. Tick the correct option.

1. The period of life, marked by rapid changes leading towards sexual maturity, is known as-

a) childhood b) old age

c) puberty d) adulthood

2. The onset of menstruation, in a human female, is known as

a) menarche b) ovulation

c) menopause d) adolescence

3. The hormone, which controls the body’s response to stress, is known as

a) insulin. b)thyroxine

c) estrogen d) adrenaline

4. Out of following, the one that does not produce hormones, is the

a) thyroid gland. b)sebaceous glands

c) pineal gland d) testes

5. The mineral, whose presence is essential for a tadpole to grow into a frog, is-

a) calcium b) chlorine

c) selenium d) iodine

D. Answer the following questions in brief.

1. State the meaning of the term ‘Adolescence’.

Ans. Adolescence is the stage of transition from childhood to adulthood. It is marked by rapid physical and mental development

2. Define puberty. State the various factors which influence it.

Ans. The period of adolescence during which an individual reach sexual maturity is called as puberty.

It is influenced by various factors like heredity and environmental factors (such as diet and exercise)

3. Why are endocrine glands known as ductless glands?

Ans. Endocrine glands are known as ductless gland as they do not have any duct of their own.

They pour their secretions directly into the blood stream.

4. Why do tadpoles growing in iodine deficient waters fail to grow into frogs?

Ans. Iodine is needed for the production of thyroxine hormone which is important to carry out the process of metamorphosis.

Therefore, tadepoles growing in iodine deficient water fail to grow into frogs.

5. How does the pituitary gland control the maturation of the gonads?

Ans. Pituitary gland secretes hormones which activate the ovaries and testes to produce oestrogen and testosterone respectively. These hormones (testosterone and oestrogen) helps in the maturation of the gonads.

6. Women, above the age of fifty, are (generally) unable to give birth to children. Explain the reason for the same.

Ans. Women above the age of fifty are unable to give birth to children due to menopause. They are now unable to produce the gametes (ovum or egg) as their menstrual cycle ceases (stop).

E. Answer the following questions.

1. Enlist the changes which occur in males and females during puberty.

Ans. In males puberty is marked by-

a) increase in height

b) change in body shape

c) change in voice

d) development of sex organs

e) growth of facial and pubic hairs.

In females puberty is marked by-

a) increase in height

b) change in body shape

c) development of sex organs

d) development of breasts.

e) appearance of pubic hairs

2. Arun and his sister Arunima are both ‘teenagers’. Arunima observes a swelling on her neck, following which she visits a doctor. The doctor identifies it to be a deficiency disease and prescribes medicines accordingly, along with suggesting dietary modifications. A few months later, Arun observes a small protrusion on his throat and visits the doctor. However, the doctor assures him that it is a normal feature in boys of his age.

a) Identify the disease Arunima was suffering from along with its cause.

Ans. Arunima was suffering from the disease called as goitre. It is caused

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