Correct Option
The correct option is 2 only
Explanation
The Rh factor (Rhesus factor) is a specific antigen found on the surface of red blood cells (RBCs). The presence or absence of this antigen determines whether a blood group is classified as Rh positive (Rh+ve) or Rh negative (Rh-ve). This classification is distinct from the ABO blood grouping system.
Statement-wise Analysis
- Statement 1 is Incorrect: Nearly 80 % of the human population possesses the Rh antigen on their red blood cells. Consequently, the majority of humans are classified as Rh positive.
- Statement 2 is Correct: Rh-negative individuals do not naturally possess anti-Rh antibodies in their plasma. However, if an Rh-negative person is exposed to Rh-positive blood (through transfusion or during pregnancy), their immune system recognizes the Rh antigen as foreign and initiates the formation of anti-Rh antibodies. Therefore, they are capable of forming these antibodies upon sensitization.
- Statement 3 is Incorrect: Rh group matching is mandatory before blood transfusion. If Rh-positive blood is transfused into an Rh-negative individual, the recipient will develop antibodies against the Rh antigen. While the first transfusion may not cause an immediate severe reaction, subsequent exposures can lead to massive destruction of RBCs (agglutination and hemolysis), which can be fatal.
Key Takeaway
Key Takeaway: Rh incompatibility triggers an immune response where an Rh-negative individual produces antibodies against Rh-positive blood upon exposure. Therefore, Rh matching is essential in transfusions and pregnancy (to prevent Erythroblastosis foetalis).