A pleiotropic gene is one which

Options

A. Affects one character
B. Affects more than one character
C. Supplements the effect of another gene
D. Required another gene for expression.

Answer

### Step-by-Step Solution:

1. **Understanding Pleiotropy**:
- Pleiotropy refers to the phenomenon where a single gene influences multiple phenotypic traits. This means that one gene can affect more than one characteristic of an organism.

2. **Definition of a Pleiotropic Gene**:
- A pleiotropic gene is defined as a gene that can produce effects on multiple traits or characteristics. This is in contrast to a gene that only influences a single trait.

3. **Examples of Pleiotropic Effects**:
- An example of a pleiotropic gene is the gene responsible for the metabolism of phenylalanine. This gene can affect various traits, such as skin pigmentation and neurological function, demonstrating how one gene can have multiple effects.

4. **Characteristics of Pleiotropic Genes**:
- It is important to note that the effects of a pleiotropic gene may not be equally pronounced across all traits. One trait may show a strong effect while another may show a weaker effect.

5. **Conclusion**:
- Therefore, a pleiotropic gene is one that affects more than one character or trait in an organism.

### Final Answer:
A pleiotropic gene is one which affects more than one character.

---