Which of the following statements is incorrect?

Options

A. Plasmids have the ability to replicate within the bacterial cells independent of the control of chromosomal DNA.
B. Some plasmids have only one or two copies per cell whereas others may have 15-100 copies per cell.
C. Bacteriophages have the ability to replicate within the bacterial cell independent of the control of chromosomal DNA.
D. Transformation is a procedure of separation and isolation of DNA fragments.

Answer

To determine which statement is incorrect among the provided options, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Analyze Statement 1**:
- **Statement**: Plasmids have the ability to replicate within the bacterial cell independent of the control of chromosomal DNA.
- **Explanation**: Plasmids are small, circular pieces of DNA that exist independently of chromosomal DNA in bacteria. They can replicate on their own without being controlled by the chromosomal DNA.
- **Conclusion**: This statement is **correct**.

2. **Analyze Statement 2**:
- **Statement**: Some plasmids have only one or two copies per cell whereas others may have 15 to 100 copies per cell.
- **Explanation**: Plasmids can vary in copy number. Some plasmids can exist in low copy numbers (1-2 copies), while others can be present in high copy numbers (up to 100 copies).
- **Conclusion**: This statement is **correct**.

3. **Analyze Statement 3**:
- **Statement**: Bacteriophages have the ability to replicate within the bacterial cell, independent of the control of chromosomal DNA.
- **Explanation**: Bacteriophages (viruses that infect bacteria) can indeed replicate within bacterial cells. They can integrate into the bacterial genome or exist independently, thus replicating without the control of the bacterial chromosomal DNA.
- **Conclusion**: This statement is **correct**.

4. **Analyze Statement 4**:
- **Statement**: Transformation is a procedure of separation and isolation of DNA fragments.
- **Explanation**: Transformation refers to the process by which genetic material (DNA) is taken up by a cell from its surroundings, leading to genetic changes. It is not a method for separating or isolating DNA fragments. The correct procedure for separation of DNA fragments is gel electrophoresis.
- **Conclusion**: This statement is **incorrect**.

### Final Answer:
The incorrect statement is **Statement 4**: "Transformation is a procedure of separation and isolation of DNA fragments."

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