The ABO blood groups in humans are expressed as the IA, IB, and i alleles. The IA allele encodes the A blood group antigen, IB encodes B, and i encodes O. Both A and B are dominant to O. If a heterozygous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate, one quarter of their offspring are expected to have the AB blood type (IAIB) in which both antigens are expressed equally. a) What other genotypes will be found? Show your work in a Punnett square.