Phenotypic and genotypic ratio is similar in case of

Options

A. complete dominance
B. incomplete dominance
C. over dominance
D. epistasis

Explanation

To solve the question regarding when the phenotypic and genotypic ratios are similar, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Phenotypic Ratio**: This is the ratio of different phenotypes (observable traits) in the offspring.
- **Genotypic Ratio**: This is the ratio of different genotypes (genetic makeup) in the offspring.

2. **Identify the Types of Dominance**:
- **Complete Dominance**: One allele completely masks the effect of another.
- **Incomplete Dominance**: Neither allele is completely dominant, resulting in a blend of traits.
- **Overdominance**: The heterozygote has a phenotype that is more extreme than either homozygote.
- **Epistasis**: One gene affects the expression of another gene.

3. **Analyze Incomplete Dominance**:
- In incomplete dominance, when two different alleles are present, the phenotype is a blend of both traits.
- For example, crossing a red flower (RR) with a white flower (rr) results in pink flowers (Rr) in the F1 generation.

4. **Perform a Cross**:
- Consider a cross between two heterozygous individuals (Rr x Rr).
- The offspring will be:
- 1 RR (Red)
- 2 Rr (Pink)
- 1 rr (White)
- This gives a phenotypic ratio of 1 Red: 2 Pink: 1 White.

5. **Calculate the Genotypic Ratio**:
- The genotypic ratio from the same cross (Rr x Rr) will also be:
- 1 RR: 2 Rr: 1 rr.
- This results in a genotypic ratio of 1:2:1.

6. **Conclusion**:
- In the case of incomplete dominance, both the phenotypic and genotypic ratios are the same (1:2:1). Therefore, the answer to the question is **incomplete dominance**.

### Final Answer:
The phenotypic and genotypic ratio is similar in the case of **incomplete dominance**.