NEET BIOLOGY

Previous
Next

GENETICS AND EVOLUTION

INHERITANCE AND VARIATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Haemophilia is a sex-linked recessive condition. A haemophiliac man has one son who has inherited haemophilia and two more sons who have not. The man’s wife is pregnant again. If this baby is a girl, what is the chance that she will have haemophilia?
A
0%
B
25%
C
50%
D
75%
Explanation: 

Detailed explanation-1: -If the son gets his mother’s X chromosome with the hemophilia gene he will have hemophilia. If he inherits his mother’s other X chromosome, he will have normal blood clotting. So a carrier’s son has a 50% chance of having hemophilia.

Detailed explanation-2: -Hemophilia is & sex-linked recessive trait in humans If a father and & son are both hemophiliacs; but the mother Is normal; her genotype must be: 0 Xhy XhXh 0 XhXh XHXH.

Detailed explanation-3: -Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern . The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes . In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition.

There is 1 question to complete.
Previous
Next