Page 69 - Genius Kidz Prudence Learning Sc-8

SECONDARY SEXUAL CHARACTERISTICS The hormones begin to be released at the

While primary sex characteristics are those onset of puberty. The production of these
that are present at birth, secondary sexual hormones is under the control of another
characteristics are those that appear during hormone secreted from endocrine gland
puberty. Many physical and emotional called pituitary gland.
changes take place in boys and girls around the In the case of girls the secondary sexual
age when they attain puberty. This period of characters are enlargement of the breasts,
life is referred to as adolescence. It is widening of the pelvic girdle, the growth of

associated with a great deal of physical and hair in pubic region and the armpits. In the
mental growth. The changes which occur in case of boys the characters are deepening of
adolescence are controlled by hormones voice caused by enlargement of larynx, growth
(chemical substances secreted by endocrine of hair on the face, chest, pubic region and
glands or endocrine system). The male armpits, enlargement of penis and scrotum
hormones are known as testosterone and and increase in muscle mass.

female hormones are known as oestrogens.

Twins born by the fertilization of two eggs are known as fracternal or non-identical twins. While in some cases the
fertilized egg may divide into two. This leads to the birth of identical twins.

! Reproduction is a biological process by which one can produce its own type.

! Reproduction can be of two types : asexual reproduction and sexual reproduction.
! Asexual reproduction involves only a single parent and sexual reproduction involves both male and
female parents.
! Puberty is the process that involves physical changes by which a child's body gets mature into an
adult body.

EXERCISE
EXERCISE

1. Multiple choice questions.
(a) Binary fission is the process of asexual reproduction in :
(i) Hydra (ii) Sponge (iii) Euglena (iv) None of these

(b) Sperm's tail helps in :
(i) Fertilization (ii) Ovulation (iii) Swimming (iv) Sperm storage
(c) Penis is responsible for :

(i) Discharge of sperms (ii) Discharge of ovum
(iii) Sperm storage (iv) None of these

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