A substance present over the surface of RBC and is genetically heritable is called

Options

A. Blood group
B. Haemoglobin
C. Antibody
D. None of these

Answer

**Step-by-Step Solution:**

1. **Identify the Substance**: The question asks for a substance present on the surface of red blood cells (RBCs) that is genetically heritable.

2. **Define Antigens**: The substances found on the surface of RBCs are known as antigens. Antigens are molecules that can trigger an immune response and are crucial in determining blood groups.

3. **Blood Group Determination**: There are two main types of antigens that determine blood groups: A and B. The presence or absence of these antigens on the RBC surface defines an individual's blood group.

4. **Blood Group Classification**:
- If A antigen is present, the blood group is A.
- If B antigen is present, the blood group is B.
- If both A and B antigens are present, the blood group is AB.
- If neither antigen is present, the blood group is O.

5. **Genetic Heritability**: The presence of these antigens is genetically inherited from parents, meaning that the blood group of an individual can be passed down through generations.

6. **Conclusion**: Therefore, the substance present over the surface of RBCs that is genetically heritable is called an "antigen."

**Final Answer**: Antigen

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