Which one of the following does not constitute the nucleic acid ?

Options

A. Uracil
B. Ribose sugar
C. Phosphoric acid
D. Guanidine

Answer

To solve the question "Which one of the following does not constitute the nucleic acid?", we will analyze the components of nucleic acids, namely DNA and RNA, and identify which option does not belong.

### Step-by-Step Solution:

1. **Understand the Components of Nucleic Acids:**
- Nucleic acids are primarily composed of three components:
- **Phosphoric acid**
- **Sugar** (which is deoxyribose in DNA and ribose in RNA)
- **Nitrogenous bases** (which include purines and pyrimidines)

2. **Identify the Types of Nucleic Acids:**
- There are two main types of nucleic acids:
- **DNA (Deoxyribonucleic Acid)**
- **RNA (Ribonucleic Acid)**

3. **List the Nitrogenous Bases:**
- The nitrogenous bases in DNA are:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
- The nitrogenous bases in RNA are:
- Adenine (A)
- Uracil (U)
- Guanine (G)
- Cytosine (C)

4. **Analyze the Given Options:**
- We need to evaluate the options provided in the question. The options include:
- **Uracil**: Present in RNA.
- **Ribose**: Present in RNA.
- **Phosphoric acid**: Present in both DNA and RNA.
- **Guanidine**: A compound used in organic synthesis but not a component of nucleic acids.

5. **Determine the Correct Answer:**
- Among the options, **guanidine** does not constitute nucleic acids, as it is not a component of either DNA or RNA.

### Conclusion:
The answer to the question is **guanidine**.

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