In the ABO blood type system,
A) A, B, and O are codominant.
B) A, B, and O are incompletely dominant.
C) A is dominant to B, and B is dominant to O.
D) O is incompletely dominant to A and B.
E) A and B are codominant.

Question

Quizplus · Accepted Answer

In the ABO blood type system, A and B are codominant, meaning that if an individual inherits both the A and B alleles, both types of antigen will be expressed on the red blood cells. This is different from incomplete dominance, where a heterozygote exhibits a phenotype that is intermediate between the two homozygous phenotypes. O blood type is recessive to A and B, meaning that an individual must inherit two copies of the O allele to exhibit the O blood type phenotype.

In the ABO Blood Type System