When a wheat variety of red karnels (homozygous for two nonallelic and independent dominant genes) is crossed with white kernelled wheat (homozygous for two recessive nonalleic independent genes), the phenotypic ratin in `F_(2)` generation would be

Options

A. `9 : 7`
B. `1 : 10 : 4 : 1`
C. `1 : 4 : 6 : 4 : 1`
D. `1 : 2 : 4 : 2 : 4 : 2 : 1`

Answer

To solve the problem, we need to analyze the genetic cross between two wheat varieties: one with red kernels (homozygous for two dominant genes) and one with white kernels (homozygous for two recessive genes).

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parents:**
- The red kernel wheat is homozygous for two dominant genes, which we can denote as R1R1 R2R2.
- The white kernel wheat is homozygous for two recessive genes, which we can denote as r1r1 r2r2.

2. **Determine the F1 Generation:**
- When we cross the two parents, all offspring in the F1 generation will inherit one dominant allele from the red kernel parent and one recessive allele from the white kernel parent. Thus, the genotype of the F1 generation will be:
- R1r1 R2r2
- The phenotype of the F1 generation will be red kernels since the dominant alleles mask the recessive alleles.

3. **Perform the F1 Cross to Obtain F2 Generation:**
- To find the F2 generation, we will cross two F1 individuals:
- (R1r1 R2r2) x (R1r1 R2r2)
- We can use a Punnett square for a dihybrid cross to determine the genotypes of the F2 generation.

4. **Construct the Punnett Square:**
- The gametes from each F1 parent will be R1R2, R1r2, r1R2, and r1r2.
- The Punnett square will show all possible combinations of these gametes.

5. **Count the Phenotypes:**
- The phenotypic ratio can be derived from the combinations of dominant and recessive traits.
- The phenotypes will include various shades of red kernels and white kernels. The typical phenotypic ratio for a dihybrid cross is 9:3:3:1. However, since we are dealing with shades of red, the ratio will be:
- 1 (dark red): 4 (medium dark red): 6 (medium red): 1 (light red): 1 (white).

6. **Final Phenotypic Ratio:**
- Therefore, the final phenotypic ratio in the F2 generation will be:
- 1 (dark red): 4 (medium dark red): 6 (medium red): 1 (light red): 1 (white).

### Conclusion:
The phenotypic ratio in the F2 generation would be 1:4:6:1:1.