Question

On what basis are human blood groups decided? How many blood groups are there in humans?

Answer 1

Blood groups are decided on the basis of presence or absence of antigens on RBCs. Antigens are small granular proteins that may or may not be present on the surface of a persons RBCs totally depending upon their genetic makeup.

There are two types of antigens found in humans, A and B.

If antigen A is present on one's cells they are said to have A - type blood group.

If antigen B is present on one's cells they are said to have B-type blood group.

If both antigens are present on the cells surface the person has an AB - type blood group.

Lastly, if no antigens are present on the cells surface, the person is said to have O - type blood group.

So in total the blood groups are A, B, AB and O.