9:6:1 `F_(2)` generation ratio is obtained in case of

Options

A. Polymeric gene
B. Pleiotropic gene
C. Supplementry genes
D. Recessive epistasis

Answer

To solve the question regarding the 9:6:1 F2 generation ratio, we will follow these steps:

### Step-by-Step Solution:

1. **Understand the Ratios**: The ratio 9:6:1 in the F2 generation indicates a specific type of genetic interaction among alleles. This ratio suggests that there are two genes involved, each contributing to the phenotype.

2. **Identify the Type of Gene Interaction**: The 9:6:1 ratio is characteristic of **polygenic inheritance**. In this case, two independent dominant genes contribute to a single trait, and when both are present, they produce a more intense phenotype.

3. **Explain the Phenotypic Effects**: In the case of polygenic inheritance, when both dominant alleles are present (homozygous or heterozygous), they produce a combined effect that results in the 9:6:1 ratio. This means:
- 9 individuals show the dominant phenotype (both genes dominant).
- 6 individuals show an intermediate phenotype (one gene dominant, one recessive).
- 1 individual shows the recessive phenotype (both genes recessive).

4. **Differentiate from Other Gene Interactions**:
- **Pleiotropic Genes** affect multiple traits but do not produce the 9:6:1 ratio.
- **Supplementary Genes** lead to a 9:3:4 ratio, not 9:6:1.
- **Recessive Epistasis** also results in a 9:3:4 ratio, where one gene masks the effect of another.

5. **Conclusion**: Therefore, the correct answer to the question is that the 9:6:1 F2 generation ratio is obtained in the case of **polygenic inheritance**.

### Final Answer:
The 9:6:1 F2 generation ratio is obtained in the case of **polygenic inheritance**.

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