The proportion of dihybrids in the `F_2` generation of a monohybrid cross ________proportion of dihybrids in the `F_2` generation of a dihybrid cross

Options

A. is same as
B. is greater than
C. is lesser than
D. may be same or greater but nevre lesser than

Answer

To solve the question regarding the proportion of dihybrids in the F2 generation of a monohybrid cross compared to the proportion of dihybrids in the F2 generation of a dihybrid cross, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Monohybrid Cross**:
- A monohybrid cross involves one trait with two alleles (e.g., Tt x Tt).
- In the F2 generation, the phenotypic ratio is typically 3:1 (dominant:recessive).
- The genotypic ratio is 1:2:1 (TT:Tt:tt).
- Here, the heterozygous condition (Tt) appears in 2 out of 4 offspring, which is 50%.

2. **Understanding Dihybrid Cross**:
- A dihybrid cross involves two traits, each with two alleles (e.g., AaBb x AaBb).
- In the F2 generation, the phenotypic ratio is typically 9:3:3:1.
- The genotypic ratio is 1:2:1 for each trait, leading to a total of 16 combinations.
- The proportion of dihybrids (heterozygous for both traits, AaBb) is 1 out of 16, which is 6.25%.

3. **Comparing Proportions**:
- In a monohybrid cross, the proportion of dihybrids (Tt) is 50%.
- In a dihybrid cross, the proportion of dihybrids (AaBb) is 6.25%.
- Therefore, the proportion of dihybrids in the F2 generation of a monohybrid cross is significantly greater than that in a dihybrid cross.

4. **Conclusion**:
- The final answer is that the proportion of dihybrids in the F2 generation of a monohybrid cross is **greater than** the proportion of dihybrids in the F2 generation of a dihybrid cross.