Q. How many phenotypes and genotypes are possible for ABO blood groups?
Solution:
| Blood Group (Phenotype) | Antigens On RBCs | Antibodies In Plasma | Gene Combination (Genotype) |
| A | A | anti-B | IAIA ; IAIi |
| B | B | anti-A | IBIB ; IBIi |
| AB | A , B | Nil | IAIB |
| O | Nil | anti-A, B | IiIi |