Final answer:
A person with A blood type can have a homozygous (IAIA) or heterozygous (IAi) genotype, while a person with AB blood has a codominant genotype (IAIB). The O blood type genotype is homozygous recessive (ii), and a person with B blood type can have a homozygous (IBIB) or heterozygous (IBi) genotype.
Step-by-step explanation:
Blood Type Genotypes
The two possible genotypes for a person who has A blood type are homozygous (IAIA) and heterozygous (IAi). A person with AB blood type has one A antigen allele and one B antigen allele, resulting in the codominant genotype (IAIB). The genotype for an individual with O blood type is homozygous recessive (ii), as both alleles are for the O antigen and neither produces the A or B antigen. Lastly, the two possible genotypes for someone with B blood type are either homozygous (IBIB) or heterozygous (IBi).
The ABO blood group system is an essential part of blood transfusions, involving three alleles (IA, IB, and i) that control the presence of specific antigens on the surface of red blood cells. In the case of type A and B blood types, each allele can exist in a dominant form (IA or IB), or a recessive form (i). The IA and IB alleles are dominant over the i allele and are codominant to each other, allowing for the AB blood type. The allele i is recessive and is not expressed in the presence of either IA or IB, leading to the O blood type when present in a homozygous state (ii).