AP BIOLOGY

Detailed explanation-1: -If a mother is heterozygous (a carrier) for hemophilia and the father does not have hemophilia, each son has a 1 in 2 (50%) chance of getting his mother’s hemophilia allele and having hemophilia. Each daughter has a 1 in 2 (50%) chance of getting her mother’s hemophilia allele and being heterozygous.

Detailed explanation-2: -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. a 25% chance of having a daughter who is a carrier.

Detailed explanation-3: -A female who inherits one affected X chromosome becomes a “carrier” of hemophilia. She can pass the affected gene on to her children. In addition, a female who is a carrier sometimes can have symptoms of hemophilia. In fact, some doctors describe these women as having mild hemophilia.

Detailed explanation-4: -Hemophilia types A and B are inherited diseases. They are passed on from parents to children through a gene on the X chromosome. Females have two X chromosomes, while males have one X and one Y chromosome. A female carrier has the hemophilia gene on one of her X chromosomes.

Detailed explanation-5: -Although hemophilia is thought of as a bleeding disorder that only affects males, females can have it too. In most cases, these females have bleeding symptoms associated with mild to moderate hemophilia, due to low levels of either factor VIII or IX.