Which of the following genes have similar genotypic effect when present separately but produce different trait after interacting together and give a ratio of 9:7 in `F _(2)` generation?

Options

A. Complementary genes
B. Jumping genes
C. Duplicate genes
D. House-keeping genes

Answer

To solve the question regarding which genes have a similar genotypic effect when present separately but produce different traits after interacting together, resulting in a 9:7 ratio in the F2 generation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Gene Interaction**:
- Begin by recognizing that certain genes can interact in such a way that they produce a combined phenotypic effect. This is known as gene interaction, which can lead to different phenotypic ratios in offspring.

2. **Identifying the Ratio**:
- The question specifies a 9:7 ratio in the F2 generation. This ratio is characteristic of complementary gene interaction, where two genes work together to produce a phenotype.

3. **Complementary Gene Interaction**:
- In complementary gene interaction, both genes must have at least one dominant allele present to express the dominant phenotype. If either gene has two recessive alleles, the phenotype will not be expressed.

4. **Genotypic Combinations**:
- Consider two genes, for example, gene A (with alleles A and a) and gene B (with alleles B and b). The combinations of these genes can be represented as:
- A_B (dominant phenotype)
- A_bb (different phenotype)
- aaB (different phenotype)
- aabb (recessive phenotype)
- The presence of at least one dominant allele from both genes is necessary for the dominant phenotype to manifest.

5. **Phenotypic Ratio Calculation**:
- When these genes interact, the resulting phenotypic ratio in the F2 generation can be calculated, leading to the 9:7 ratio:
- 9 individuals show the dominant phenotype (A_B)
- 7 individuals show the recessive phenotype (aabb, A_bb, aaB)

6. **Conclusion**:
- Therefore, the genes that exhibit this pattern of interaction are known as complementary genes. They have similar genotypic effects when present separately but produce different traits when they interact together, resulting in a 9:7 ratio in the F2 generation.

### Final Answer:
The genes that have similar genotypic effects when present separately but produce different traits after interacting together, resulting in a 9:7 ratio in the F2 generation, are **complementary genes**.