Science
Write notes on :
(a) Adam's apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
Adolescence
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Answer
(a) Adam's apple — At puberty, the voice box or the larynx begins to grow. Boys develop larger voice boxes. The growing voice box in boys can be seen as a protruding part of the throat called Adam's apple. Sometimes, the muscles of the growing voice box go out of control and the voice becomes hoarse. This state may remain for a few days or weeks after which the voice becomes normal.
(b) Secondary sexual characters — Secondary sexual characters are responsible for the features that help to distinguish the male from the female. Secondary sexual characters in boys are development of pubic hair, facial hair and hair on chest. Development of breast in girls is also a secondary sexual character.
(c) Sex determination in the unborn baby — All human beings have 23 pairs of chromosomes in the nuclei of their cells. Two chromosomes out of these are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised egg always has one X chromosome. But sperms are of two kinds. One kind has an X chromosome, and the other kind has a Y chromosome. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child.
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