The gene which affect more than one phenotype called pleiotropic gene.

Answer

**Step-by-Step Solution:**

1. **Understanding the Definition of Pleiotropic Genes:**
- A pleiotropic gene is defined as a single gene that has multiple effects on different phenotypic traits. This means that one gene can influence various characteristics in an organism.

2. **Examples of Pleiotropic Effects:**
- An example of a pleiotropic gene is the gene responsible for the color of the coat in certain animals, which may also affect other traits such as the animal's size or health. This illustrates how one gene can have diverse effects.

3. **Importance in Genetics:**
- Pleiotropic genes are significant in genetics because they help explain how certain traits are interconnected and how a single genetic change can lead to multiple phenotypic outcomes.

4. **Conclusion:**
- Therefore, the statement that "the gene which affects more than one phenotype is called a pleiotropic gene" is indeed true.

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