Page 113 - Science Class 08

Adolescence : Period of life when the body undergo changes leading to reproductive
maturity

Puberty : The stage at which our body undergoes various bodily changes
Hormone : A substance in our body released by different glands that co-ordinates
activities of the body and its growth
Gland : A small bag like structure inside our body

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i Growth is a natural process in all living beings which begins from the day they are born.
i The period of life when the body undergoes changes leading to reproductive maturity is
called adolescence.
i Adolescence generally begins around the age of 11 and lasts upto 18 or 19 years of age.

i Adolescents are also called teenagers.
i Various bodily changes take place during the period of adolescence. These changes mark the
onset of puberty.
i At the age of puberty, the activity of the sweat and sebaceous glands increases and they have
more secretion.
i At the age of adolescence, both the boys and girls also become more conscious.

i Physical changes that occur during the period of adolescence are caused by the secretion of
chemical substances by the endocrine glands. These chemical substances are called
hormones.
i There are two types of glands namely exocrine glands and endocrine glands.
i Exocrine glands secrete chemical substances directly into ducts.
i Pituitary gland secretes the most number of hormones.

i Adrenal gland secrete two types of hormones namely adrenaline and corticoids.

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A. Tick (3) the correct op on.
1. At what age adolescence generally begins?
(a) 5 years (b) 20 years

(c) 11 years (d) 13 years
2. Which of the following is not a secondary sexual character?
(a) Growth of facial hair in boys
(b) Growth of breasts in girls

(c) Growth of hair under armpit in both boys and girls
(d) Change in voice

Science-8 113