Question

“The chromosomes number of the sexually reproducing parents and their offspring is the same.” Justify this statement.

Answer 1

Among the 46 chromosomes, 44 chromosomes are related to phenotypic inheritance only 2 chromosomes are involved in genotypic inheritance. During the gamete fusion and formation of offspring the chromosome number remains the same as that of the parents.

Complete answer:
To answer this question, we should know about distribution of sex chromosome by the parents to their offspring. To understand the chromosomal distribution we should know that in humans, we have 23 pairs of chromosomes, among these 22 pairs are autosomes while one pair is termed as sex chromosome. This one pair helps in determining the sex of an individual. In humans females have 2X chromosomes that they received from each parent and males have one X and one Y chromosomes that they receive from each of the parents. Male in humans have one X chromosome and one Y chromosome that they get from each of their parents, that is, one from mother and one from father.

Now, sexual reproduction involves the fusion of male and female gametes. As a result, the chromosome number in gametes is half of the chromosome number in somatic cells. Therefore, during fertilization, the number of chromosomes becomes equal to that of the somatic cells. Hence, the offspring and the parents of an organism that undergo sexual reproduction have the same number of chromosomes.

Note: Any abnormality in the sex chromosome causes sexual disorders like monosomy that is missing of whole sex chromosome, trisomy inclusion of one extra chromosome. Klinfelter’s syndrome and Turner’s syndrome are the sexual disorders cause due to addition and deletion of sex chromosomes.