This question refers to the ABO blood type locus. Remember that the A and B alleles are codominant to each other and both are dominant to the O allele. Assume no epistatic interactions with the H locus. A man has blood type A. Mark all genotypes below that are possible for this man. Select one or more: AA AB AO BB BO OO Solution Hence both A and B are codominant and dominant over O, the possible genotype of man having blood group A are AA and AO. Explanation: As both A and B are codominant if both are present iegenotype AB results in AB blood group BB and BO results in B blood group (as there is no A in genotype and B is dominant over O) OO results in O bllod group(Absence of both A and B in genotype).