Transfer of bacterial genes by a phage is called:

Options

A. Transformation
B. Transduction
C. Conjugation
D. Hybridisation

Answer

To answer the question "Transfer of bacterial genes by a phage is called:", we need to analyze the options provided and understand the processes involved in bacterial gene transfer.

### Step-by-Step Solution:

1. **Understanding the Options**: The question presents four options: Transformation, Transduction, Conjugation, and Hybridization. We need to identify which of these involves the transfer of bacterial genes specifically by a phage.

2. **Defining Transformation**: Transformation is a process where bacteria take up naked DNA from their environment. This does not involve a phage, so this option is incorrect.

3. **Defining Transduction**: Transduction is the process where bacterial DNA is transferred from one bacterium to another by a bacteriophage (a virus that infects bacteria). This matches the question's requirement of gene transfer by a phage.

4. **Defining Conjugation**: Conjugation involves the direct transfer of DNA between two bacteria through a physical connection called a conjugation tube. This process does not involve a phage, making this option incorrect.

5. **Defining Hybridization**: Hybridization generally refers to the process of combining different varieties of organisms or DNA strands and is not a method of gene transfer in bacteria. Thus, this option is also incorrect.

6. **Conclusion**: Based on the definitions and processes discussed, the correct answer to the question is **Transduction**, as it specifically involves the transfer of bacterial genes by a phage.

### Final Answer:
The transfer of bacterial genes by a phage is called **Transduction**.

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