`F_(2)` generation of a cross between two white flowered strains of Sweet Pea yields 9 purple flowered plants: 7 white flowered plants. This is an example is

Options

A. Epistasis
B. Complementary genes
C. Supplementary genes
D. Gene inhibition.

Answer

To solve the question regarding the F2 generation of a cross between two white flowered strains of Sweet Pea yielding a ratio of 9 purple flowered plants to 7 white flowered plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Phenotypic Ratio**:
The given ratio of 9 purple flowered plants to 7 white flowered plants suggests a specific genetic interaction.

2. **Identify the Cross**:
The problem states that the cross is between two white flowered strains of Sweet Pea. This indicates that both parent plants are homozygous for the white flower trait.

3. **Determine the Genotypes**:
Let’s assume that the purple flower trait is dominant over the white flower trait. The genotypes can be represented as follows:
- Let "P" represent the dominant allele for purple flowers.
- Let "p" represent the recessive allele for white flowers.
- The white flowered strains could be "pp" (homozygous recessive).

4. **Perform the Cross**:
When two white flowered plants (pp x pp) are crossed, they do not produce any purple flowers in the F1 generation. However, if we consider a scenario where the white flowers are due to epistatic interactions, we can assume that there are other genes involved.

5. **Analyze the F2 Generation**:
In the F2 generation, the observed ratio of 9:7 suggests that there are complementary genes at play. This means that two different genes are required to produce the purple flower phenotype, and the presence of at least one dominant allele from each gene is necessary to express the purple color.

6. **Conclusion**:
Based on the 9:7 ratio, this is an example of complementary gene interaction (also known as epistasis). Therefore, the correct answer to the question is that this is an example of complementary genes.

### Final Answer:
This is an example of complementary genes.

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