Cross over value (COV) of genes A and B is `5%` while COV of genes B and C is `15%` the possible sequence of these genes on chromosome is :-

Options

A. `A-B-C`
B. `C-A-B`
C. `B-C-A`
D. Both (1) & (2)

Answer

To determine the possible sequence of genes A, B, and C on a chromosome based on their crossover values (COV), we can follow these steps:

### Step-by-Step Solution:

1. **Understand Crossover Value (COV)**:
- The crossover value between two genes indicates the percentage of recombinant offspring produced due to crossing over during meiosis. A lower COV indicates that the genes are closer together on the chromosome, while a higher COV indicates they are farther apart.

2. **Identify Given COV Values**:
- The COV between genes A and B is 5%.
- The COV between genes B and C is 15%.

3. **Calculate COV Between A and C**:
- To find the COV between genes A and C, we can add the COV values:
\[ \text{COV (A to C)} = \text{COV (A to B)} + \text{COV (B to C)} = 5\% + 15\% = 20\% \]

4. **Visualize Gene Arrangement**:
- We can visualize the arrangement of the genes on a chromosome. If we place gene A first, followed by gene B, and then gene C, we can represent it as:
- A — (5%) — B — (15%) — C
- This arrangement suggests that A is closest to B, and B is closest to C.

5. **Determine the Sequence**:
- Based on the COV values and the arrangement, the most logical sequence of the genes on the chromosome is:
- **A, B, C**

6. **Evaluate Other Options**:
- Any other arrangement (like A, C, B or B, A, C) would not maintain the given COV values correctly. Thus, A, B, C is the only correct sequence.

### Conclusion:
The possible sequence of these genes on the chromosome is **A, B, C**.

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