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. rrrr
B. RR
C. Rr
D. rr

Answer

To determine the genotype of the two Antirrhinum plants with pink flowers that were hybridized, we can follow these steps:

### Step 1: Understand the Flower Color Genetics
In Antirrhinum, the flower color is determined by two alleles:
- **Red flowers** are represented by the genotype **RR** (homozygous dominant).
- **White flowers** are represented by the genotype **rr** (homozygous recessive).
- **Pink flowers** are represented by the genotype **Rr** (heterozygous), which results from incomplete dominance.

### Step 2: Analyze the F1 Generation
The problem states that when two pink-flowered plants were hybridized, the F1 generation produced flowers in the ratio of:
- 1 Red : 2 Pink : 1 White

This indicates that the F1 generation must have been produced from a cross of two plants that can produce both red and white flowers.

### Step 3: Determine Possible Parent Genotypes
Given that the F1 generation produced red, pink, and white flowers, we need to find the genotypes of the parent plants. Since pink flowers (Rr) were the result of the hybridization, we can conclude that both parent plants must have contributed the R allele.

### Step 4: Set Up the Cross
If we assume the two parent plants were both heterozygous (Rr), we can set up the cross:
- Parent 1: Rr (Pink)
- Parent 2: Rr (Pink)

### Step 5: Use a Punnett Square
We can use a Punnett square to visualize the potential offspring:
```
R r
----------------
R | RR | Rr |
----------------
r | Rr | rr |
----------------
```

From this Punnett square, we can see the offspring ratios:
- 1 RR (Red)
- 2 Rr (Pink)
- 1 rr (White)

This gives us the ratio of 1 Red : 2 Pink : 1 White, which matches the observed F1 generation.

### Step 6: Conclusion
Thus, the genotype of the two plants used for hybridization is **Rr** (both plants being heterozygous).

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

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