In Cucurbita, W is epistatic over Y and y gene normally responsible for yellow and green colour fruits. It produces white flowers. What is the ratio of fruits in the progeny of cross `WwYy xx wwYy` ?

Options

A. 9 white : 7 yellow : 0 green
B. 3 white : 4 yellow : 1 green
C. 4 white : 3 yellow : 1 green
D. 2 white : 1 yellow : 1 green

Answer

To solve the problem of determining the ratio of fruits in the progeny of the cross `WwYy x wwYy`, we will follow these steps:

### Step 1: Identify the Genotypes
We have two parents:
- Parent 1: `WwYy` (heterozygous for both traits)
- Parent 2: `wwYy` (homozygous recessive for W and heterozygous for Y)

### Step 2: Determine Gametes
Next, we will determine the possible gametes produced by each parent:
- Parent 1 (`WwYy`) can produce the following gametes: `WY`, `Wy`, `wY`, `wy`
- Parent 2 (`wwYy`) can produce the following gametes: `wY`, `wy`

### Step 3: Set Up a Punnett Square
Now, we will set up a Punnett square to visualize the combinations of these gametes:

| | wY | wy |
|---------|---------|---------|
| **WY** | WwYy | Wwyy |
| **Wy** | WwYy | Wwyy |
| **wY** | wwYy | wwyy |
| **wy** | wwYy | wwyy |

### Step 4: Determine the Phenotypes
Now we will determine the phenotypes for each genotype:
- `WwYy`: White fruit (W is epistatic over Y)
- `Wwyy`: White fruit (W is epistatic over y)
- `wwYy`: Yellow fruit (since both alleles for W are recessive)
- `wwyy`: Green fruit (both alleles for W and Y are recessive)

### Step 5: Count the Phenotypes
From the Punnett square, we can count the phenotypes:
- White fruits: `WwYy` (2) + `Wwyy` (2) = 4
- Yellow fruits: `wwYy` (2) = 2
- Green fruits: `wwyy` (2) = 1

### Step 6: Calculate the Ratio
The final ratio of the fruits in the progeny is:
- White : Yellow : Green = 4 : 2 : 1

### Final Answer
The ratio of fruits in the progeny of the cross `WwYy x wwYy` is **4:2:1**.

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