When a cluster of genes shows linkage behaviour they

Options

A. do not show independent assortment
B. induce cell division
C. do not show a chromosome map
D. show recombination meiosis

Explanation

**Step-by-Step Solution:**

1. **Understanding Linkage Behavior:**
- Linkage refers to the phenomenon where genes that are located close to each other on the same chromosome tend to be inherited together. This is because they are physically linked and do not assort independently during gamete formation.

2. **Analyzing the Options:**
- **Option 1: They do not show independent assortment.**
- This is true for linked genes. Since they are located close together on the same chromosome, they tend to be inherited together rather than assorting independently.
- **Option 2: Induce cell division.**
- This option is not relevant to the concept of gene linkage. Cell division is a separate biological process.
- **Option 3: Do not show chromosome map.**
- This is incorrect. Linkage can be mapped on chromosomes, and linkage maps can be created based on the frequency of recombination between genes.
- **Option 4: Show pre-combination mucosis.**
- This option does not accurately describe the behavior of linked genes. Recombination occurs during meiosis, but linked genes do not show recombination as frequently as unlinked genes.

3. **Conclusion:**
- Based on the analysis, the correct answer is **Option 1: They do not show independent assortment.** This reflects the behavior of linked genes during gamete formation.