A plan with red coloured folowers is crossed with a plant having white fllowes. The red and white colour of the flower is controlled by a single gene. Red is domainan over white. The F1 progeny is self-pollinated and the flower colour in F2 is observed. Given the above information what is the expected phenotypic ratio of plants with different flower colours ?

Options

A. All plants with red flowr
B. Red : while in the ratio of 3 : 1
C. Pink : while in the ratio of 3 : 1
D. Red : pink : white in a ratio of 1 : 2 : 1

Explanation

To solve the problem of flower color inheritance in plants, we will follow these steps:

### Step 1: Identify the parental genotypes
- The plant with red flowers is homozygous dominant (RR).
- The plant with white flowers is homozygous recessive (rr).

### Step 2: Determine the F1 generation
- When we cross the red flower plant (RR) with the white flower plant (rr), all offspring in the F1 generation will inherit one allele from each parent.
- Therefore, the genotype of all F1 progeny will be Rr (heterozygous).
- Since red (R) is dominant over white (r), all F1 plants will exhibit the red flower phenotype.

### Step 3: Self-pollinate the F1 generation
- Now, we will self-pollinate the F1 generation (Rr x Rr).
- The gametes produced by each F1 plant will be R and r.

### Step 4: Use a Punnett square to find the F2 generation
- Set up a Punnett square to determine the genotypes of the F2 generation:

```
R r
------------
R | RR | Rr |
------------
r | Rr | rr |
```

### Step 5: Analyze the genotypes from the Punnett square
- From the Punnett square, we can see the following genotypes:
- 1 RR (homozygous red)
- 2 Rr (heterozygous red)
- 1 rr (homozygous white)

### Step 6: Determine the phenotypic ratio
- The phenotypes corresponding to these genotypes are:
- 3 red flowers (1 RR + 2 Rr)
- 1 white flower (1 rr)
- Therefore, the expected phenotypic ratio of the F2 generation is 3 red : 1 white.

### Final Answer
The expected phenotypic ratio of plants with different flower colors in the F2 generation is **3:1** (3 red : 1 white).

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