Question

Which blood group is known as the universal donor?

• A. A
• B. B
• C. AB
• D. O

Hint:

Remember:
- Universal Donor: O (no A or B antigens on RBCs)
- Universal Recipient: AB (no anti-A or anti-B antibodies in plasma)
Always consider the Rh factor (Rh-negative for universal donor, Rh-positive for universal recipient) for complete compatibility.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks to identify the human blood group that can be donated to individuals of any other ABO blood group without causing a major immune reaction, hence known as the "universal donor."

Step 3: Detailed Explanation:
The ABO blood group system is based on the presence or absence of specific antigens (A and B) on the surface of red blood cells (RBCs) and corresponding antibodies (anti-A and anti-B) in the plasma.
- Blood Group O: Individuals with blood group O have neither A nor B antigens on their RBCs. This absence of antigens means that their red blood cells will not be recognized as foreign by the recipient's immune system, regardless of the recipient's ABO blood group. However, Group O individuals have both anti-A and anti-B antibodies in their plasma. Therefore, Group O blood (specifically O negative for universal donor for Rh factor also) can be transfused to individuals of any other ABO blood group, making it the universal donor.
- Blood Group A: Has A antigens, anti-B antibodies.
- Blood Group B: Has B antigens, anti-A antibodies.
- Blood Group AB: Has both A and B antigens, no anti-A or anti-B antibodies. It is the universal recipient.

Step 4: Final Answer:
Blood group O is known as the universal donor.