Mendel's dihybrid ratio is

Options

A. `15:1`
B. `9:3:3:1`
C. `1:2:1`
D. `9:6:1`

Answer

To solve the question regarding Mendel's dihybrid ratio, we will follow these steps:

### Step 1: Understand the Concept of Dihybrid Cross
A dihybrid cross involves two traits, each represented by two alleles. For example, consider two traits: seed shape (round vs. wrinkled) and seed color (yellow vs. green).

### Step 2: Determine the Parental Genotypes
Assume the parental genotypes are:
- Round yellow seeds (RRYY)
- Wrinkled green seeds (rryy)

### Step 3: Perform the Dihybrid Cross
When these two parental genotypes are crossed, the F1 generation will all be heterozygous (RrYy).

### Step 4: Create a Punnett Square
To find the F2 generation, create a 4x4 Punnett square using the gametes from the F1 generation (RY, Ry, rY, ry).

### Step 5: Count the Phenotypes
From the Punnett square, the phenotypic ratio can be counted:
- Round Yellow (RY) = 9
- Round Green (rY) = 3
- Wrinkled Yellow (Ry) = 3
- Wrinkled Green (ry) = 1

### Step 6: State the Dihybrid Ratio
The final phenotypic ratio for a dihybrid cross is 9:3:3:1.

### Conclusion
Thus, Mendel's dihybrid ratio is **9:3:3:1**.

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