In Mirabills jalapa , the homozygous white(rr) and Red (RR) flower colour produces pink (Pr) flower colour. When a pink flower is crossed with red flower, the ratio will be

Options

A. 25% white : 50% pink : 25% red
B. 50% pink : 50% red
C. 50% pink : 50% white
D. 50% red : 50% white

Answer

To solve the problem, we need to analyze the genetic cross between the pink flower (Pr) and the red flower (RR) in Mirabilis jalapa, where the inheritance pattern shows incomplete dominance.

### Step-by-Step Solution:

1. **Identify the Genotypes:**
- The homozygous red flower has the genotype RR.
- The pink flower, which is a result of the cross between homozygous red (RR) and homozygous white (rr), has the genotype Rr (since it exhibits incomplete dominance).

2. **Set Up the Cross:**
- We are crossing a pink flower (Rr) with a red flower (RR).

3. **Determine the Gametes:**
- The pink flower (Rr) can produce two types of gametes: R and r.
- The red flower (RR) can only produce one type of gamete: R.

4. **Create a Punnett Square:**
- Set up a Punnett square to visualize the cross:

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

5. **Analyze the Results:**
- From the Punnett square, we can see the offspring genotypes:
- 2 squares show RR (red flowers)
- 2 squares show Rr (pink flowers)
- Therefore, the ratio of the offspring is:
- 2 red flowers (RR) : 2 pink flowers (Rr) or simplified, 1 red : 1 pink.

6. **Conclusion:**
- The final ratio of flower colors when a pink flower is crossed with a red flower is 1:1, meaning 50% red and 50% pink.