Epistatic gene differs from dominant gene in

Options

A. Epistatic gene is nonallelic
B. Epistatic gene never expressed itself independently
C. Epistatic and hypostatic genes are present at different loci
D. All the above

Answer

### Step-by-Step Solution:

1. **Definition of Epistatic Gene**: An epistatic gene is a gene that can mask or suppress the expression of another gene at a different locus. This means that the effect of one gene can be overridden by the presence of another gene.

2. **Definition of Dominant Gene**: A dominant gene is one that expresses its trait even when only one copy is present (heterozygous condition). It can express itself independently without being influenced by other genes.

3. **Allelic vs. Non-allelic**:
- **Epistatic genes** are non-allelic, meaning they are located at different loci on the chromosome and do not compete for the same gene position.
- **Dominant genes** are allelic, meaning they are located at the same locus and can have different alleles (e.g., dominant and recessive).

4. **Expression Independence**:
- **Epistatic genes** do not express themselves independently; their expression is dependent on the presence of other genes.
- **Dominant genes** can express themselves independently, meaning their expression is not affected by the presence of other genes.

5. **Loci Position**:
- **Epistatic genes** and their corresponding hypostatic genes (the genes being masked) are present at different loci.
- **Dominant genes** are present at the same locus, where they can interact with their alleles.

6. **Effect on Other Genes**:
- **Epistatic genes** can hide or mask the effect of another gene, meaning they can prevent the expression of the hypostatic gene.
- **Dominant genes** do not hide the effects of other genes; they simply express their own traits.

7. **Law of Independent Assortment**:
- The law of independent assortment does not apply to epistatic genes because their expression is interdependent.
- The law of independent assortment applies to dominant genes, as they can segregate independently during gamete formation.

8. **Conclusion**: Therefore, the epistatic gene differs from the dominant gene in several ways: it is non-allelic, does not express itself independently, and is present at different loci. Thus, the correct answer is "all the above."