Question

Which blood group is called a universal donor?
A. AB
B. A
C. B
D. O

Answer 1

The different blood groups are based on the presence or absence of antigens on the surface of RBCs. A blood transfusion between two people can only happen when there is compatibility amongst the antigen and antibodies in the serum. A universal donor should not have antigens on the RBCs as the antibodies in the recipient’s blood would counter them.

Complete answer: Blood group O is called the Universal Donor. The different blood groups are based on the presence or absence of surface antigens A and B on the red blood cells. When neither A nor B surface antigens are there on the RBCs, the blood group is O. Since the blood group O does not contain surface antigens (antigen A or/and B), the antibodies in a receiver’s body would not cause an immune response against the transfused blood. Due to this reason, people with blood group O can donate their blood to any person having any blood group. Therefore, they are correctly referred to as universal donors.
Hence, the correct answer is Option D.
Additional information:
When antigen A is present on the RBCs, the blood group is A. In this case, the serum of the person would contain B antibodies. When antigen B is present on the RBCs, the blood group is B. In this case, the serum of the person would contain A antibodies. When both antigens A and B are present on the RBCs, the blood group would be AB. In this case, there would be neither A antibodies nor B antibodies present in the serum.

Note: It is important to check the blood group of an individual before transfusion. Blood transfusion between two incompatible blood groups can lead to serious complications. Antigen-antibody reactions can cause blockage in the blood vessels. Before a transfusion, the blood should also be tested and screened for bacteria, viruses, or any other infectious agent that can cause problems in the recipient.