AP BIOLOGY

Detailed explanation-1: -A female with the hemophilia gene is called a hemophilia carrier. Females have two X chromosomes, so the presence of the hemophilia gene on one X does not result in hemophilia. The presence of the normal gene that codes for the production of factor compensates for the defective gene that does not.

Detailed explanation-2: -If the mother has one altered factor gene and the father does not have hemophilia, each son has a 50% chance of having hemophilia and each daughter has a 50% chance of having one altered factor gene, causing her to be a carrier or have hemophilia.

Detailed explanation-3: -Males having one normal gene and females having two normal genes for Factor VIII are clear of the hemophilia A trait and will not transmit this defect to offspring. Males having one abnormal gene are affected with hemophilia and will transmit that abnormal gene to all their daughters, but to none of their sons.

Detailed explanation-4: -A man who has hemophilia and a woman who is a carrier have: a 25% (one in four) chance of having a son with hemophilia. a 25% chance of having a son with normal blood clotting.