ABO blood grouping in humans in an example of

Options

A. Polygenic inheritance
B. Multiple allelism
C. Epistasis
D. Pleiotropic inheritance

Answer

To answer the question "ABO blood grouping in humans is an example of," we will analyze the concepts of polygenic inheritance, multiple allelism, epistasis, and pleiotropic inheritance step by step.

### Step-by-Step Solution:

1. **Understanding Polygenic Inheritance**:
- Polygenic inheritance refers to a situation where multiple genes (more than two) contribute to a single phenotype. An example of this is skin color in humans, where several genes interact to produce a range of skin tones.
- **Hint**: Think of traits that show a continuous range, like height or skin color.

2. **Understanding Multiple Allelism**:
- Multiple allelism occurs when there are more than two alleles for a particular gene in a population. In the case of ABO blood groups, there are three alleles: IA, IB, and i.
- Although there are three alleles, an individual can only inherit two alleles (one from each parent). This leads to four possible blood types: A, B, AB, and O.
- **Hint**: Remember that multiple alleles mean more than two variations of a gene, but individuals can only have two at a time.

3. **Understanding Epistasis**:
- Epistasis is a genetic interaction where one gene can mask or suppress the expression of another gene. An example is seen in mice coat color, where one gene can affect the expression of another.
- **Hint**: Think about how one gene can influence or hide the effects of another gene.

4. **Understanding Pleiotropic Inheritance**:
- Pleiotropic inheritance occurs when a single gene influences multiple phenotypic traits. An example is sickle cell anemia, where one gene affects red blood cell shape and various health issues.
- **Hint**: Consider how one gene can have multiple effects on an organism.

5. **Conclusion**:
- After analyzing the definitions and examples of each term, we conclude that ABO blood grouping in humans is an example of **multiple allelism**. This is because there are three alleles (IA, IB, and i) that determine the blood type, but an individual can only possess two of these alleles at a time, leading to the four blood types: A, B, AB, and O.

### Final Answer:
ABO blood grouping in humans is an example of **multiple allelism**.