Blood Types A O B AB Donor Recipient Genotype Phenotype Antigen Antibody Homozygous. Remember your Punnett square problems? 4 Genotypes AB Ao Bo oo 4. Best Answer: If the type A parent is heterozygous, then the offspring can be expected to have either type O or type A in a ratio of 1:1; If the type A. A parent of blood type O is homozygous recessive for the i allele. The Punnett square for their offspring is shown to the right. Blood Type Punnett Square Practice There are four major blood groups determined by the presence or absence of two antigens (proteins) – A and B – on the surface. In this example, the Punnett square is used to determine the possible blood types of the father while the mother is confirmed Type O and all TEENren are. Blood type Punnett squares are done just like other Punnett squares . if the man is type AB, then his genotype is AB; he produces A and B gametes.