Phenotypic and genotypic ratio in `F_(2)` generation in incomplete dominance is

Options

A. 1:2:1 and 1:2:1
B. 3:1 and 1:2:1
C. 9:6 and 3:1
D. 9:3:3:1 and 1:2:1:4:1:1:2:1:2:1

Answer

To determine the phenotypic and genotypic ratios in the F2 generation for incomplete dominance, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Incomplete Dominance**:
- Incomplete dominance occurs when neither allele is completely dominant over the other. As a result, the phenotype of the heterozygous individual is a blend of the two parental traits.

2. **Example of Incomplete Dominance**:
- A classic example is the flower color in the plant *Mirabilis jalapa* (commonly known as four o'clock plant). If one parent has red flowers (RR) and the other has white flowers (WW), the F1 generation (all heterozygous RW) will have pink flowers.

3. **F1 Generation**:
- The F1 generation consists of all heterozygous individuals (RW), which display the intermediate phenotype (pink flowers).

4. **F2 Generation**:
- When the F1 individuals (RW) are self-crossed (RW x RW), we can set up a Punnett square to determine the genotypes of the F2 generation:
- The possible combinations will be:
- RR (red)
- RW (pink)
- WW (white)

5. **Genotypic Ratio**:
- The genotypes from the Punnett square will be:
- 1 RR : 2 RW : 1 WW
- Therefore, the genotypic ratio is **1:2:1**.

6. **Phenotypic Ratio**:
- The phenotypes from the same Punnett square will be:
- 1 Red (RR) : 2 Pink (RW) : 1 White (WW)
- Therefore, the phenotypic ratio is also **1:2:1**.

7. **Conclusion**:
- In incomplete dominance, both the phenotypic and genotypic ratios in the F2 generation are the same: **1:2:1**.

### Final Answer:
- The phenotypic and genotypic ratio in the F2 generation in incomplete dominance is **1:2:1**.