Question

Universal donor is
(a)O Rh+
(b)O Rh-
(c)AB Rh+
(d)AB Rh-

Answer 1

Hint: Universal donor refers to those blood groups that can be donated to all groups. The human blood group contains A, B, and Rh antigens and a and b antibodies. A person with blood group O has no antigens. They have a and b antibodies.

Complete answer:
Blood group O- is the universal donor because it neither has antigen for blood group nor it has the antigen for Rh factor. A group contains 'A' antigen and b antibody it can receive A and the O group and can be donated to A and AB groups, without any danger. B group contains B antigen and antibody a, it can receive B and O group and can be donated to B and AB groups. AB-group contains antigens A and B and no antibodies. So, it can receive all groups, and at the same time can be donated only to AB groups. Similarly, O-group contains antibodies a & b, but no antigens. So, it can be donated to all groups but can receive only O groups. Since AB-group can receive all groups and O-group can be donated to all groups, they are known respectively as the universal recipient and the universal donor. Landsteiner and Weiner independently discovered a previously unknown antigen in the RBCs of the rhesus monkey. Persons possessing the Rh antigen are called Rh-positive (Rh+ve), and those lacking it are called Rh-negative(Rh-ve) persons can always receive Rh-ve blood without any complications. But an Rh-ve person can receive Rh +ve blood with no risk only once.

Additional Information: -Blood transfusion is the transfer or administration of one person’s blood to another’s body.
- The person who donates blood is called the donor, and the person who receives blood is called the recipient. It is not safe to transfuse blood from any donor indiscriminately to any recipient.
- The blood of different individuals can be chemically different and when two different types of blood are mixed together, they may sometimes interact.
So, the correct answer is ' O Rh-'

Note: -mutually interacting types of blood are said to be incompatible or mismatching. Those which do not interact are called compatible or matching types.
 -Transfusion of incompatible blood causes the death of the recipient. This is because of the clumping or agglutination of the donor's red corpuscles in the recipient.
-Agglutination is the result of an antigen-antibody reaction. The antigen is known as agglutinogen and the antibody agglutinin.