The enzyme which has polymerising activity in `5' to 3'` direction but exonuclease activity in `3' to 5'` direction only is :-

Options

A. RNA polymerase III
B. DNA polymerase II
C. DNA polymerase I
D. All of these

Answer

To solve the question regarding the enzyme that has polymerizing activity in the 5' to 3' direction and exonuclease activity in the 3' to 5' direction, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**:
- We need to identify an enzyme that has two specific activities:
- Polymerizing activity in the 5' to 3' direction.
- Exonuclease activity in the 3' to 5' direction.

2. **Recall Enzyme Functions**:
- Enzymes involved in DNA replication typically have polymerizing activity, which means they can add nucleotides to a growing DNA strand.
- Exonuclease activity refers to the ability of an enzyme to remove nucleotides from the ends of a DNA strand.

3. **Identify the Enzyme**:
- The enzyme that fits the description is **DNA polymerase**. Specifically, we are looking for **DNA polymerase III** (often referred to simply as DNA polymerase in many contexts).
- DNA polymerase synthesizes new DNA strands by adding nucleotides in the 5' to 3' direction.
- It also has a 3' to 5' exonuclease activity, which allows it to proofread and correct errors during DNA replication.

4. **Choose the Correct Option**:
- Based on the options provided, the correct answer is **DNA polymerase III**.

### Final Answer:
The enzyme which has polymerizing activity in the 5' to 3' direction but exonuclease activity in the 3' to 5' direction only is **DNA polymerase III**.

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