Write notes on −

(a) Adam’s apple.

(b) Secondary sexual characters.

(c) Sex determination in the unborn baby.

(a) Adam's apple:

In human males, the larynx grows larger during puberty and can be seen as a protruding part of the throat. This protrusion is known as Adam's apple. In boys, under the influence of hormones, the larynx becomes prominent. As a result, the vocal cords become longer and thicker, causing the voice to become hoarse. However, in females, the larynx is of small size and is hardly visible. Therefore, girls have a high pitched voice, while the sound of boys is low pitched.

(b) Secondary characters are those features that help in distinguishing the male and the female body from each other. They are physical or behavioural characteristics that appear in humans at the time of puberty.

Secondary characters in boys:

(i) The appearance of moustache and beard.

(ii) The appearance of chest hair.

(iii) Growth of hair in the genital area and other parts of the skin.

A secondary character in girls:

(i) Growth of hair in the genital area and other body parts.

(c) Gender determination in an unborn baby:

The gender of a baby is determined by the type of male gamete that fuses with the female gamete.

All human beings have 23 pairs of chromosomes in their nuclei. Out of these 23 pairs, the last couple is known as the sex chromosome.

The human males have 23 pairs of chromosomes, including XY chromosomes. Therefore, the male gamete has 22 chromosomes and either an X or Y chromosome.

Male gametes can be of two types: 22+X or 22+Y

Females have 23 pairs of chromosomes, including XX chromosomes. Therefore, their gametes can only have 22 chromosomes and one X chromosome.

Thus, as the mother provides only X chromosome, the gender of the baby is determined by the type of male gamete (X or Y) that fuses with the X chromosome of the female.