R- gene present on plasmid is meant for

Options

A. Drug resistance
B. Nitrogen fixation
C. Locomotion
D. Exchange of genetic material.

Answer

### Step-by-Step Solution:

1. **Understanding Plasmids**:
- Plasmids are small, circular, double-stranded DNA molecules that are separate from chromosomal DNA. They are primarily found in bacteria and can replicate independently.

2. **Function of Plasmids**:
- Plasmids often carry genes that provide bacteria with advantageous traits. These traits can include antibiotic resistance, metabolic capabilities, or the ability to produce certain proteins.

3. **Identifying the R Gene**:
- The R gene, or resistance gene, is specifically associated with providing bacteria the ability to resist the effects of antibiotics. This means that bacteria with the R gene can survive in environments where antibiotics are present.

4. **Evaluating the Options**:
- **Drug Resistance**: This is the correct function of the R gene as it directly relates to the ability of bacteria to survive antibiotic treatment.
- **Nitrogen Fixation**: This is not related to plasmids; nitrogen-fixing capabilities are typically associated with specific bacteria, not plasmid genes.
- **Locomotion**: Bacterial locomotion is usually facilitated by structures like flagella, not plasmid genes.
- **Exchange of Genetic Material**: While plasmids can be involved in genetic exchange, the specific plasmid responsible for this is known as the F-plasmid, not the R gene.

5. **Conclusion**:
- Based on the analysis, the R gene present on plasmids is meant for **drug resistance**.

### Final Answer:
The R gene present on plasmid is meant for **drug resistance**.

---