Human Blood Groups
What are the blood groups?
Although all human blood looks red and is basically made up of the same plasma, cells, etc., the presence or absence of certain protein molecules in the blood divide the kinds of bloodinto different groups. There can be four different types or groups of blood and evey person can be classified under one of these. These groups are called A,B,O and AB. Anthropogists who study the physical development of the human race, use blood groups as one of the ways of showing relationships among individuals and population groups.
The four blood groups can further be divided into subgroups. If a person has to be given blood because of some physical problem, it is essential to give him the blood which matches has blood. If the blood from two different group is mixed, a reaction between the protein molecules in the red cells and the plasma makes the blood clump. These chemical reactions make it dangerous for a person to receive a blood transfusion from someone with a different blood group.
If the cells are remoed from blood, then the remaining plasma can be given to anyone even if the blood groups are different.