In Antirrhinium two plants with pink flowers were hybridized. The `F_(1)` plants producedred, pink and white flowers in the proportion of 1 red, 2 pink and1 white. What could be the genotype of the two plants used for hybridization. Red flower colour is determined by RR, and white rr genes

Options

A. rr
B. Rr
C. RR
D. rrrr

Answer

To solve the problem, we need to determine the genotypes of the two Antirrhinum plants that were hybridized, given that they produced red, pink, and white flowers in a 1:2:1 ratio in the F2 generation.

### Step-by-Step Solution:

1. **Understand the Flower Color Genetics**:
- Red flower color is represented by the genotype **RR** (homozygous dominant).
- White flower color is represented by the genotype **rr** (homozygous recessive).
- Pink flower color is produced by the heterozygous genotype **Rr** (incomplete dominance).

2. **Analyze the F1 Generation**:
- The problem states that two plants with pink flowers were hybridized. Since pink flowers are produced by the **Rr** genotype, we can conclude that both parent plants must have been **Rr**.

3. **Determine the F2 Generation**:
- When two **Rr** plants are crossed, we can set up a Punnett square to determine the genotypes of the offspring:
```
Gametes from Parent 1: R, r
Gametes from Parent 2: R, r

| | R | r |
|---|---|---|
| R | RR| Rr|
| r | Rr| rr|
```
- The resulting genotypes from this cross are:
- **1 RR** (Red)
- **2 Rr** (Pink)
- **1 rr** (White)

4. **Phenotypic Ratio**:
- From the Punnett square, we see that the phenotypic ratio is:
- 1 Red (RR) : 2 Pink (Rr) : 1 White (rr)
- This matches the given ratio of 1 red, 2 pink, and 1 white.

5. **Conclusion**:
- Since the only way to achieve this ratio is by crossing two pink flowered plants (both with the genotype **Rr**), we conclude that the genotype of the two plants used for hybridization is **Rr**.

### Final Answer:
The genotype of the two plants used for hybridization is **Rr** (heterozygous).

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