Find the odd one out w.r.t complete linkage

Options

A. `100%` parental combinations in `F_(2)` generation
B. `F_(2)` phenotypic ratio is `3:1` in monohybrid cross
C. Dihybrid test cross ratio is `1:1` in `F_(2)` generation
D. Linked genes tend to separate frequently

Answer

To solve the question "Find the odd one out with respect to complete linkage," we will analyze each option provided in the context of complete linkage.

### Step-by-Step Solution:

1. **Understand Complete Linkage**:
- Complete linkage occurs when genes are very close together on a chromosome, leading to the inheritance of parental combinations without any recombinant types during gamete formation.

2. **Analyze Each Option**:
- **Option 1**: "100% parental combinations in F2 generation"
- This statement is true for complete linkage because, in complete linkage, only parental types are produced, and no recombinants are formed.

- **Option 2**: "F2 phenotypic ratio is 3:1 in monohybrid cross"
- This statement is also true. In a monohybrid cross involving a single gene, the phenotypic ratio remains 3:1 regardless of linkage, as it does not affect the segregation of a single gene.

- **Option 3**: "Dihybrid test cross ratio is 1:1 in F2 generation"
- This statement is true as well. In a dihybrid test cross, if complete linkage is present, the ratio of offspring will reflect the parental combinations, leading to a 1:1 ratio for the linked genes.

- **Option 4**: "Linked genes tend to separate frequently"
- This statement is false in the context of complete linkage. In complete linkage, linked genes do not separate frequently; instead, they are inherited together.

3. **Identify the Odd One Out**:
- After analyzing all the options, it is clear that **Option 4** is the odd one out because it contradicts the principle of complete linkage.

### Conclusion:
The correct answer is **Option 4: linked genes tend to separate frequently**.

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