what produces type o phenotype
The A and B alleles are dominant to the O allele. When both inherited alleles are O, the genotpye is homozygous recessive and the blood type is O. When one of the inherited alleles is A and the other is B, the genotype is heterozygous and the blood type is AB.AB blood type is an example of co-dominance since both traits are expressed equally.1  Type A: The genotype is either AA or AO. 2  Type B: The genotype is either BB or BO. 3  Type AB: The genotype is AB. 4  Type O: The genotype is OO.B blood type is an example of co-dominance since both traits are expressed equally. 1  Type A: The genotype is either AA or AO. 2  Type B: The genotype is either BB or BO. 3  Type AB: The genotype is AB. 4  Type O: The genotype is OO.