In `F_(2)` generation, a ratio of 1:4:6:4:1 is obtained instead of 9:3:3:1, when two pairs of genes are considered, it indicates

Options

A. incomplete dominance
B. quantitative inherritance
C. qualitative inheritance
D. pleiotropic effect of genes

Answer

To solve the question regarding the ratio obtained in the F2 generation when considering two pairs of genes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Ratios**:
- The typical Mendelian ratio for a dihybrid cross (two pairs of genes) is 9:3:3:1. This represents the phenotypic ratio of offspring when two traits are independently assorted.
- However, in this case, the observed ratio is 1:4:6:4:1.

2. **Analyzing the Given Ratio**:
- The ratio 1:4:6:4:1 suggests that the traits are not assorting independently. Instead, it indicates a cumulative effect of multiple alleles contributing to a single phenotype.

3. **Identifying the Type of Inheritance**:
- The observed 1:4:6:4:1 ratio is characteristic of **quantitative inheritance**, also known as polygenic inheritance. This type of inheritance occurs when multiple genes influence a single trait, leading to a range of phenotypes.

4. **Conclusion**:
- Since the question provides options and the correct interpretation of the ratio aligns with the concept of quantitative inheritance, we conclude that the correct answer is **quantitative inheritance** (Option B).

### Final Answer:
The ratio of 1:4:6:4:1 in the F2 generation indicates **quantitative inheritance**.

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