Given below are four statements pertaining to separation of DNA fragments using gel electrophoresis. Identify the incorrect statements.
(a) DNA is negatively charged molecule and so it is loaded on gel towards the Anode terminal
(b) DNA fragments travel along the surface of the gel whose concentration does not affect movement of DNA.
(c) Smaller the size of DNA fragment larger is the distance it travels through it.
(d) Pure DNA can be visualized directly by exposing UV radiation.
Choose correct answer from the options given below

Options

A. (a), (c) and (d)
B. (a), (b) and (c)
C. (b), (c) and (d)
D. (a), (b) and (d)

Answer

To identify the incorrect statements regarding the separation of DNA fragments using gel electrophoresis, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A**: "DNA is a negatively charged molecule and so it is loaded on the gel towards the Anode terminal."
- **Analysis**: DNA is indeed negatively charged. However, it is loaded on the gel at the cathode (negative terminal) so that it can migrate towards the anode (positive terminal) when the electric field is applied. Therefore, this statement is incorrect.

2. **Statement B**: "DNA fragments travel along the surface of the gel whose concentration does not affect movement of DNA."
- **Analysis**: The concentration of the gel does affect the movement of DNA fragments. A higher concentration of agarose gel provides a greater sieving effect, which can impede the movement of larger DNA fragments while allowing smaller fragments to move more freely. Thus, this statement is also incorrect.

3. **Statement C**: "Smaller the size of DNA fragment larger is the distance it travels through it."
- **Analysis**: This statement is correct. Smaller DNA fragments can navigate through the pores of the gel more easily and thus travel further compared to larger fragments, which are hindered by the gel matrix.

4. **Statement D**: "Pure DNA can be visualized directly by exposing UV radiation."
- **Analysis**: This statement is incorrect. Pure DNA cannot be visualized directly under UV light. It must first be stained (commonly with ethidium bromide) to visualize it as bands under UV light. Therefore, this statement is also incorrect.

### Conclusion:
The incorrect statements are A, B, and D.

### Final Answer:
The incorrect statements are A, B, and D.

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