What is the human ABO blood group system?

ABO blood group system. biology. ABO blood group system, the classification of human blood based on the inherited properties of red blood cells (erythrocytes) as determined by the presence or absence of the antigens A and B, which are carried on the surface of the red cell

Explanation:

combination of alleles

traits, however, alleles may be codominant-i. e., neither acts as dominant or recessive. An example is the human ABO blood system; persons with type AB blood have one allele for A and one for B. (Persons with neither are type O.) See also dominance; recessiveness.