Question

Describe the chromosomal theory of sex determination.

Answer 1

Hint: A chromosomal theory of the sex-determination system is a biological system that controls the event of sexual characteristics in an organism. Most organisms that create their offspring using sexual reproduction have two sexes– male and female.

Complete answer:
Chromosome plays an important role in determining the sex of an individual. Chromosomes are a thread-like structure holding genetic information. It is present in the cell nuclei. A normal cell contains 23 pairs (46n) of chromosomes. Out of these, one pair (2n) is sex chromosomes. Sex chromosomes are denoted as X and Y. A male cell carries XY sex chromosomes while a female cell carries XX sex chromosomes. A gamete contains only 23 chromosomes (23n). Sperm carries either an X or Y chromosome, i.e. there will be two sets of sperms. One set of sperm made up of only X chromosomes, while another set made up of only Y chromosomes. An ovum always carries an X chromosome. The sex of the kid depends on the type of sperm that fuses with the ovum. During sexual intercourse, the father ejects both types of sperms, i.e. X chromosome and Y chromosome sperms. 1. If the sperm with an X chromosome fertilizes the ovum of the X chromosome, the zygote would have XX chromosomes, and the child will be a girl. 2. If the sperm with the Y chromosome fertilizes the ovum of the X chromosome, then the zygote would have XY chromosomes, and the child will be a boy.

Note: Fertilization is the process in which two gametes that are sperm and ova, fuse together to form a new cell called the zygote. During this unbiased event, all genetic information from parents to the kid has been transferred. Also, the gender of the kid is decided, and therefore the father of the kid is liable for sex determination.