2025 · Q113
What are the four human blood types in ABO blood group typing?
General KnowledgeBiology
- AAO , BO, A and B
- BA, B, AB and O
- CA, AB, BO and O
- DAB, AO , B and O
Explanation
The ABO blood group system classifies human blood into four types — A, B, AB and O — based on the antigens present on red blood cells. (Genotypes such as AO and BO are not blood types.) Type O red cells carry neither A nor B antigen, while type AB carries both. This classification, discovered by Karl Landsteiner, underpins safe blood transfusion.