Question

Match the following:

Column A	Column B
1. Male sex chromosome	a. 23
2. Female sex chromosome	b. 46
3. Pair of chromosomes in human	c. XX
d. XY

a) 1-c, 2-d, 3-b
b) 1-d, 2-c, 3-a
c) 1-b, 2-a, 3-c
d) 1-d, 2-a, 3-b

Answer 1

Humans have 23 pairs of chromosomes but they are not the same in males and females. The males have odd sets of chromosomes which are not similar but in females, the chromosomes are alike.

Complete answer:
The human reproductive cell in females carries only a single chromosome, which is the X chromosome. The sperm cell, or the male reproductive cell in humans carries either X or Y chromosome. Thus, the gender of a human offspring is defined by the sperm cell fertilizing the egg cell. If X chromosome carrying a sperm cell fertilizes the egg cell, the offspring is female, otherwise the offspring is a male. Hence, the female sex chromosome in humans is of the type XX and that of males is XY.
The total number of chromosomes in humans is 46, which appear in 23 pairs. This happens because during the meiosis cell division, only 23 chromosomes are distributed in the cells which ensures that after fertilization, the chromosomes are paired and 46 chromosomes are restored in the humans. The chromosomes are responsible for the making up of the genetic framework of an individual.

Therefore, option D is the correct answer as all the options match with appropriate justification of the facts.

Note:
Chromosomes are divided into two categories in humans – autosomes and genomes. The autosomes are 22 pairs and are responsible for the genetic traits in an individual. The genomes are the sex chromosomes which are responsible for the gender of the individual.