X' is physiologically and biologically active from of DNA . The pitch of its helix is `34Å` with a distance between two adjacent base pair of about `3.4Å` It shows right-handed coiling. Identify 'X'

Options

A. B - DNA
B. A - DNA
C. Z - DNA
D. C - DNA

Answer

To solve the question, we need to identify the form of DNA referred to as 'X' based on the provided characteristics. Here’s a step-by-step breakdown of the solution:

### Step 1: Analyze the Characteristics
The question states that 'X' is a physiologically and biologically active form of DNA. The characteristics given are:
- Pitch of the helix: 34 Å
- Distance between two adjacent base pairs: 3.4 Å
- Right-handed coiling

### Step 2: Recall the Forms of DNA
There are several forms of DNA, including:
- A-DNA
- B-DNA
- Z-DNA
- C-DNA
- D-DNA

Among these, B-DNA is known to be the most common and biologically active form found in living organisms.

### Step 3: Compare with Known Characteristics of B-DNA
B-DNA has the following characteristics:
- Pitch of the helix: 34 Å
- Distance between adjacent base pairs: 3.4 Å
- Right-handed coiling

These characteristics match perfectly with those provided in the question.

### Step 4: Eliminate Other Forms of DNA
- A-DNA: Has a different pitch and is not the most common form.
- Z-DNA: Has a pitch of 46 Å and is left-handed coiling.
- C-DNA and D-DNA: Are less common and not typically found in physiological conditions.

### Conclusion
Based on the analysis, the form of DNA 'X' that is physiologically and biologically active, with a pitch of 34 Å, a distance of 3.4 Å between base pairs, and right-handed coiling is **B-DNA**.

### Final Answer
**X is B-DNA.**

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