The percentage of a recombinants in the `F_(2)` of a typical dihybrid cross is

Options

A. 50
B. 25
C. 37.5
D. 62.5

Answer

To determine the percentage of recombinants in the F2 generation of a typical dihybrid cross, we can follow these steps:

### Step-by-Step Solution:

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

2. **F1 Generation**: When two true-breeding parents (e.g., round yellow seeds and wrinkled green seeds) are crossed, the F1 generation will be heterozygous for both traits (e.g., RrYy, where R = round, r = wrinkled, Y = yellow, y = green).

3. **Self-Crossing F1 Generation**: The F1 individuals are then self-crossed (RrYy x RrYy) to produce the F2 generation.

4. **F2 Generation Phenotypic Ratio**: The phenotypic ratio of the F2 generation from a dihybrid cross is typically 9:3:3:1. This means:
- 9 individuals show both dominant traits (round and yellow),
- 3 individuals show the dominant trait for the first character and recessive for the second (round and green),
- 3 individuals show the recessive trait for the first character and dominant for the second (wrinkled and yellow),
- 1 individual shows both recessive traits (wrinkled and green).

5. **Identifying Recombinants**: The recombinant phenotypes are those that do not match the parental combinations. In this case, the recombinant phenotypes are the ones represented by the 3:3 ratios (round and green, wrinkled and yellow).

6. **Calculating Recombinant Percentage**:
- Total phenotypes = 16 (9 + 3 + 3 + 1)
- Recombinant phenotypes = 6 (3 from round-green and 3 from wrinkled-yellow)
- Therefore, the percentage of recombinants = (Number of Recombinants / Total Phenotypes) × 100 = (6/16) × 100 = 37.5%.

### Final Answer:
The percentage of recombinants in the F2 generation of a typical dihybrid cross is **37.5%**.

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