Question

Study the statements given below.
X: In humans, the gamete contributed by the male determines whether the child produced will be male or female.

Y: Sex in humans is a polygenic trait depending upon a cumulative effect of some genes on X chromosome and some on Y chromosome.

• A. If both X and Y are true and the Y is the correct explanation of the X.
• B. If both X and Y are true but Y is not the correct explanation of the X.
• C. If X is true but Y is false.
• D. If both X and Y are false.

Answer 1

Answer: (C)

If X is true but Y is false.

Human females have XX chromosomes and males have XY chromosomes. The sperm may contain either X or Y chromosome. The sperm is the factor in deciding the sex of the child. If the sperm carries an X chromosome, it will fuse with the egg’s X chromosome to form a female. If the sperm carries a Y chromosome, it will result in a male child. Hence the gamete contributed by the male determines whether the child produced will be male or female. The genes which interact to have an effect on the same character are called polygenic traits. No interaction takes place between the genes on the X and Y chromosome. The presence of the chromosome decides the sex of the child.

Thus the correct answer is option C.