A person with blood group O will have _____ antibody/antibodies in plasma.

Options

A. anti-B
B. anti-A
C. nil
D. anti-A and anti-B

Answer

To determine the antibodies present in the plasma of a person with blood group O, we need to understand the relationship between blood groups, antigens, and antibodies. Here's a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Blood Groups**: Blood groups are determined by the presence or absence of specific antigens on the surface of red blood cells (RBCs). The main blood group system is the ABO system, which includes blood groups A, B, AB, and O.

2. **Antigens and Alleles**:
- The ABO blood group system is controlled by three alleles: IA (A antigen), IB (B antigen), and i (no antigen, which corresponds to blood group O).
- Individuals with blood group O have the genotype ii, meaning they do not produce A or B antigens on their RBCs.

3. **Antibodies in Plasma**:
- Antibodies are proteins produced by the immune system in response to foreign antigens. They are present in the plasma of the blood.
- The antibodies produced are specific to the antigens that are not present on the individual's own RBCs.

4. **Blood Group O Characteristics**:
- Since individuals with blood group O do not have A or B antigens on their RBCs, their immune system recognizes both A and B antigens as foreign.
- Therefore, they produce antibodies against both A and B antigens.

5. **Conclusion**:
- A person with blood group O will have both anti-A and anti-B antibodies in their plasma.

### Final Answer:
A person with blood group O will have **both A and B antibodies** in plasma.

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