In Antirrhinum (dog flower), phenotypic ratio in `F_(2)` generation for the inheritance of flower colour would be

Options

A. `3:1`
B. `1:2:1`
C. `1:1`
D. `2:1`

Explanation

To determine the phenotypic ratio in the F2 generation for the inheritance of flower color in Antirrhinum (dog flower), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Traits**:
- In Antirrhinum, there are two flower colors: red and white.
- The red color is represented by the dominant allele (R) and the white color by the recessive allele (r).

2. **Cross the Parental Generation**:
- When we cross two purebred plants, one with red flowers (RR) and the other with white flowers (rr), we get the F1 generation.
- The cross can be represented as:
\[ RR \times rr \rightarrow Rr \text{ (all offspring are heterozygous red)} \]

3. **Self-Pollination of F1 Generation**:
- The F1 generation (Rr) is then self-pollinated to produce the F2 generation.
- The cross for the F2 generation can be represented as:
\[ Rr \times Rr \]

4. **Punnett Square**:
- We can set up a Punnett square to determine the genotypes of the F2 generation:
\[ \begin{array}{c|c|c} & R & r \\ \hline R & RR & Rr \\ \hline r & Rr & rr \\ \end{array} \]
- From this, we can see the genotypes produced:
- 1 RR (red)
- 2 Rr (red)
- 1 rr (white)

5. **Determine the Phenotypic Ratio**:
- The phenotypes corresponding to these genotypes are:
- RR: Red
- Rr: Red
- rr: White
- Therefore, the phenotypic ratio is:
\[ 3 \text{ (red)} : 1 \text{ (white)} \]

6. **Conclusion**:
- The phenotypic ratio in the F2 generation for the inheritance of flower color in Antirrhinum is **3:1**.

### Final Answer:
The phenotypic ratio in the F2 generation for the inheritance of flower color in Antirrhinum (dog flower) is **3:1**.

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