Select the incorrect statement :

Options

A. The normal E.coil cell carry resistance against ampicillin , tetracycline and kanamycin etc.
B. Separated DNA fragments can be visualized only after staining the DNA
C. You can see pure DNA framgemets in the visible light without staining
D. Both (1) and (3)

Answer

To solve the question "Select the incorrect statement," we will analyze each of the provided statements one by one to identify which ones are incorrect.

### Step-by-Step Solution:

1. **Evaluate Statement 1**:
- The statement claims that "the normal E. coli cell carries resistance against ampicillin, tetracycline, and kanamycin."
- This statement is incorrect because normal E. coli does not have inherent resistance to these antibiotics. Resistance is typically conferred through genetic modification or plasmid insertion.

2. **Evaluate Statement 2**:
- The statement says, "separated DNA fragments can be visualized only after staining the DNA."
- This statement is correct. DNA fragments need to be stained (for example, with ethidium bromide) to be visualized, especially after gel electrophoresis.

3. **Evaluate Statement 3**:
- The statement claims, "you can see pure DNA fragments in the visible light without staining."
- This statement is incorrect. Pure DNA fragments cannot be visualized in visible light without staining; they require staining and observation under UV light after electrophoresis.

4. **Evaluate Statement 4**:
- The statement states, "both 1 and 3."
- Since both Statement 1 and Statement 3 are incorrect, this statement is also correct in identifying the incorrect statements.

### Conclusion:
The incorrect statements are both 1 and 3, making option 4 the correct answer to the question.

### Final Answer:
**Option 4: Both 1 and 3.**

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