Genotype of a person with “A” blood group can be I
AI
O or I
AI
A and that of parent with AB blood group is I
AI
B. The alleles I
A, I
O and I
B can make three genotypic combinations, namely I
AI
A, I
AI
O, I
AI
B and I
BI
O. Thus, the possible blood group of their children are A, B and AB. To have a child with O blood group, both parent should have at least one I
O allele; thus they can’t have a child with O blood group. This makes option A, C and D wrong. Correct answer is E.
Cross 1
Parent generation : I
A I
A x (I
A I
B)