Question : A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits - blood group A or O - is dominant. Why or why not ?

Question : A man with blood group A marries a woman with blood group O

1.	Question : A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits - blood group A or O - is dominant. Why or why not ?
Answer» Solution :Given: Man with blood GROUP A, so genotype may be `I^(A)" "I^(A)" or "I^(A)` i. Woman with blood group O, so genotype will be ii. Daughter.s blood group is O, so blood group will be i i. This cross clearly shows that the daughter MUST get two genes from two PARENTS. Since mother has both RECESSIVE genes, she can give only recessive gene. This implies that father must have genotype `I^(A)` i (for blood group A) so as to be able to give other .i. to the daughter Since blood group O is expressed only in homozygous recessive situation ie., .i i hence it is recessive trait. Blood group .A. is a DOMINANT trait as it expressed even in heterozygous condition. Thus this information is enough.