Question

What is the probability of X-linked genes being passed from father to son?
A. $0\%$
B. $25\%$
C. $50\%$
D. $100\%$

Answer 1

The X and Y chromosomes are two types of sex chromosomes. Females typically have two X chromosomes (XX). Her mother gives her one X chromosome and her father gives her the other. Males typically have both an X and Y chromosome (XY). The mother’s X chromosome is inherited, while the father’s Y chromosome is inherited.

Complete answer:
$0\%$: If a man with an X-linked condition produces a son, the altered gene on the X chromosome will never be passed down to his son. Because men always pass on their Y chromosome to their sons, this is the case. If a father has a daughter with an X-linked condition, he will always pass on the altered gene to her. This is due to the fact that males have just one X chromosome, which they invariably pass on to their daughters. As a result, all of his daughters will be carriers. The illness normally does not affect the girls, but they are at danger of having affected sons. Hence there is $0\%$ probability that X-linked genes are passed from father to son.

So, option A is the correct answer.

Additional information :
$25\%$: There is zero percent probability that X-linked genes are being passed from father to son. Hence option B is not correct.
$50\%$: If the mother has an X-linked gene, then there is $50\%$ probability that it would get passed on to her son or daughter. But there is no probability that the X-linked gene can be passed from father to son. Hence option C is not correct
$100\%$: The probability of X-linked genes to be passed from father to daughter is$100\%$, since the father has only one X gene. But there is no probability that the X-linked gene can pass on to his son. Hence option D is not correct.

Note :
If a female carrier has a son, the X chromosome with the normal gene or the X chromosome with the changed gene will be passed down. As a result, each son has a $50\%$ chance of inheriting the altered gene and being impacted by the disease. A $50$ percent possibility exists that the son will inherit the normal gene. He will not be affected by the condition if this occurs. Every son has an equal chance.