When a single gene influences more then one trait it is called

Options

A. pseudodominance
B. pleiotropy
C. epistasis
D. none of these

Answer

To answer the question "When a single gene influences more than one trait it is called," we will analyze the options provided and identify the correct term that describes this genetic phenomenon.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a term that describes the situation where one gene affects multiple traits. This is a key concept in genetics.

2. **Analyzing the Options**:
- **Option A: Pseudodominance**: This term refers to a situation where a recessive trait appears to be dominant due to the presence of a single recessive allele. It does not relate to a single gene influencing multiple traits.
- **Option B: Pleiotropy**: This is the correct term. Pleiotropy occurs when one gene influences multiple phenotypic traits. An example of pleiotropy is seen in phenylketonuria (PKU), where a single gene mutation affects multiple traits such as metabolism and neurological development.
- **Option C: Apoptosis**: This term refers to programmed cell death and is not related to the influence of a single gene on multiple traits.
- **Option D: None of these**: This option is incorrect since we have already identified the correct term.

3. **Selecting the Correct Answer**: Based on the analysis, the correct answer is **Option B: Pleiotropy**.

### Final Answer:
When a single gene influences more than one trait, it is called **pleiotropy**.

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