Biology · May / June 2020 · Paper 11 · Question 39

The inheritance of the ABO blood groups in humans is controlled by three alleles (I^A, I^B and I^O), only two of which can be present in one individual. What are the possible blood groups of children born to a homozygous group A woman and a heterozygous group B man?

1. AAB and B only
2. BAB and A only
3. CA, B and AB only
4. DA, B, AB and O

As printed in the paper