Which of the following statements is incorrect ?

Options

A. A person of 'O' blood group has anti 'A' and anti 'B' antibodies in his blood plasma.
B. A person of 'B' blood group cannot donate blood to a person of 'A' blood group .
C. Blood group is designated on the basis of the presence of antibodie in the blood plasma.
D. A person of AB blood group is universal recipient.

Answer

To determine which of the following statements is incorrect regarding blood groups, let's analyze each statement one by one:

1. **Statement A**: A person of O blood group has anti-A and anti-B antibodies in his blood.
- **Analysis**: This statement is true. Individuals with O blood type do indeed have both anti-A and anti-B antibodies in their plasma, which is why they cannot receive blood from A or B blood types.

2. **Statement B**: A person of B blood group cannot donate blood to a person of A blood group.
- **Analysis**: This statement is also true. A person with B blood type has B antigens and anti-A antibodies. If they donate blood to someone with A blood type, the anti-A antibodies will attack the A antigens, leading to a serious reaction.

3. **Statement C**: Blood group is designated on the basis of presence of antibodies in the blood plasma.
- **Analysis**: This statement is incorrect. Blood groups are actually determined by the presence of specific antigens on the surface of red blood cells (RBCs), not by the antibodies in the plasma. Therefore, this statement is false.

4. **Statement D**: A person of AB blood group is a universal recipient.
- **Analysis**: This statement is true. Individuals with AB blood type have both A and B antigens and no antibodies against A or B, allowing them to receive blood from any blood group (A, B, AB, or O) without risk of an immune reaction.

**Conclusion**: The incorrect statement is **C**: "Blood group is designated on the basis of presence of antibodies in the blood plasma."