Ratio of parental and recombinant phenotypes in a dihybrid cross would be

Options

A. `8:8`
B. `6:10`
C. `10:6`
D. `9:7`

Answer

To solve the question regarding the ratio of parental and recombinant phenotypes in a 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, let's consider two traits: seed shape (round vs. wrinkled) and seed color (yellow vs. green).

2. **Identify Parental Genotypes**: In a typical dihybrid cross, we start with two parental genotypes. For instance, one parent may be homozygous for round yellow seeds (RRYY) and the other homozygous for wrinkled green seeds (rryy).

3. **F1 Generation**: The F1 generation from this cross will all be heterozygous (RrYy) and display the dominant traits (round yellow seeds).

4. **F2 Generation**: When the F1 generation is self-fertilized (RrYy x RrYy), the F2 generation will exhibit a phenotypic ratio based on Mendelian genetics. The expected phenotypic ratio in the F2 generation is 9:3:3:1 for the four possible phenotypes.

5. **Identify Parental and Recombinant Phenotypes**:
- Parental phenotypes: Round Yellow (RRYY or RrYy) and Wrinkled Green (rryy).
- Recombinant phenotypes: Round Green (Rryy) and Yellow Wrinkled (rrYy).

6. **Count the Progeny**: In a typical dihybrid cross, out of 16 offspring:
- 10 will show parental phenotypes (9 Round Yellow + 1 Wrinkled Green).
- 6 will show recombinant phenotypes (3 Round Green + 3 Yellow Wrinkled).

7. **Calculate the Ratio**: The ratio of parental to recombinant phenotypes is therefore 10:6, which can be simplified to 5:3.

### Final Answer:
The ratio of parental to recombinant phenotypes in a dihybrid cross is **10:6**.

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