Question

A man with type a blood marries a woman with type b blood. their child has type o blood. what are the genotypes of these three individuals? what genotypes, and in what frequencies, would you expect in future offspring from this marriage?

Answer 1

If someone has blood type A, they must have atleast one copy of the A allele, but they could have two copies. Their genotype is either AA or AO. while an individual with blood type B will have a genotype of either BB or BO. Individuals with type O blood will have a genotype OO. Both A and B alleles are dominant over O.
Therefore, the genotype of the man is AO, that of the mother is BO, while that of the child is OO.
In future from this marriage, the possible genotypes are;
AO, BO, AB, or OO
In the frequency of 1/4 each.