OBJECTIVE LIFE SCIENCE
GENETICS
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
All sons will have hemophilia
|
|
|
all daughters will have hemophilia
|
|
|
50% of daughters and 50% of sons have hemophilia
|
|
|
100% of sons have hemophilia and 100% of daughters are carriers
|
Detailed explanation-1: -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-2: -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-3: -Thus the correct answer is (D) 50% sons will have haemophilia. Note: Haemophilia is X recessive linked gene disorder. A carrier mother has 50% chance of transferring the disease to her daughter. An affected male will pass on the genes to the daughters.