Inheritance of ABO blood groups is an example of

Options

A. Epistasis
B. Multiple allelism
C. Pletropism
D. Complementary genes

Answer

To solve the question regarding the inheritance of ABO blood groups, we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding ABO Blood Groups**:
- The ABO blood group system consists of four main blood types: A, B, AB, and O.
- These blood groups are determined by the presence of specific antigens on the surface of red blood cells.

2. **Identifying the Alleles**:
- The ABO blood groups are controlled by three alleles:
- IA (which produces A antigen),
- IB (which produces B antigen), and
- i (which does not produce any antigen).
- The combinations of these alleles determine the blood type:
- IAIA or IAi results in blood type A,
- IBIB or IBi results in blood type B,
- IAIB results in blood type AB,
- ii results in blood type O.

3. **Co-dominance**:
- The alleles IA and IB exhibit co-dominance, meaning that when both are present (in the case of blood type AB), both antigens are expressed.

4. **Analyzing the Options**:
- **Epistasis**: This refers to the interaction between genes, where one gene can mask or modify the expression of another gene. This does not apply here as we are dealing with alleles of the same gene.
- **Multiple Allelism**: This is the correct term for the situation where more than two alleles exist for a particular gene. In this case, there are three alleles (IA, IB, and i) controlling the ABO blood groups.
- **Pleiotropism**: This refers to a single gene affecting multiple phenotypic traits. This does not apply to the ABO blood group system.
- **Complementary Genes**: This involves two different genes that work together to produce a single characteristic. This is not relevant to the ABO blood groups.

5. **Conclusion**:
- The inheritance of ABO blood groups is an example of **multiple allelism** because it involves three different alleles that determine the blood type.

### Final Answer:
The inheritance of ABO blood groups is an example of **multiple allelism**.

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