Q.8 Write notes on—
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
(a) Adam’s apple – In male at puberty, the voice box, or the larynx begins to grow. The growing voice box in boys can be seen as a protruding part of the throat that is called Adam’s apple.
Under the influence of sex hormone, the larynx becomes prominent that results the vocal cords become longer and thicker which cause the voice to become hoarse.
(b) Secondary sexual character-
The feature which helps to distinguish between male and female is known as a secondary sexual character.
Secondary Sexual Characters in girls-
- Growth of hair in the genital area underarms and other body parts.
- Size of breast starts developing and the skin of nipple which is present at the tip of the breasts starts to darkening.
Secondary Sexual Characters in boys-
- Growing to facial hair that is moustaches, and beard.
- Growth of hair in the genital area underarm and other body parts.
- The appearance of chest hair
(c) Sex determination in unborn baby-
The sex of the unborn baby is determined by the type of male gamete which fuses with the female gamete.
All human beings have 23 pair of chromosomes in the nuclei of their cell.
Out of these two chromosomes are sex chromosomes – X and Y.
Female have 23 pair of chromosomes including XX sex chromosomes.
Therefore, female gamete can only have 22 chromosomes and one X chromosome.
Male gamete can have two kinds, one has an X chromosome and other has a Y chromosome.
They have 23 pair of chromosome including XY sex chromosome.
Male gamete – 22+X or 22+ Y
Female gamete – 22+X
So, the sex chromosome of the father determines the sex of the unborn baby. So the father is responsible for the sex of the unborn baby and we all believe that the mother is responsible for the sex of the unborn baby is completely wrong.