In the ABO system of blood groups if both antigens are present but no antibody, the blood group of the individual would be :-
A
O
B
AB
C
A
D
B
The answer is B.
Solution
Blood group A has antigen A on the RBCs and anti-B antibodies in the plasma. Blood group B has antigen B and anti-A antibodies. Blood group AB has both antigens A and B, and no antibodies (so it is the universal recipient). Blood group O has no antigens and both anti-A and anti-B antibodies (universal donor). So an individual with both antigens and no antibody has blood group AB (genotype $I^AI^B$, an example of codominance).
ConceptAntigens and antibodies in AB blood group
Multiple alleles - ABO blood groups in past papers
4 questions from this chapter have appeared across 4 exam years.
