Why do we have different blood types?

Answer: Proteins on red blood cells vary

Blood types prevent all diseases — Wrong. Blood types don't prevent all diseases. They determine compatibility for transfusions and may affect susceptibility to certain conditions.

Proteins on red blood cells vary ✓ — Correct! Blood types (A, B, AB, O) are determined by specific proteins (antigens) on the surface of red blood cells. These are inherited from parents. The immune system recognizes foreign blood types and attacks them, which is why matching blood types is important for transfusions.

Geographic location changes blood — Wrong. Blood type is genetic and doesn't change based on where you live. It's determined by inherited genes from your parents.