Uridine, present only in RNA is

Options

A. Pyrimidine
B. Nucleoside
C. Nucleotide
D. Purine

Answer

To solve the question "Uridine, present only in RNA is," we will analyze the options provided and determine the correct classification of uridine.

### Step-by-Step Solution:

1. **Understanding Uridine**:
- Uridine is a nucleoside that consists of a nitrogenous base (uracil) and a sugar (ribose). It does not contain a phosphate group.

2. **Identifying the Options**:
- The options provided are:
1. Pyrimidine
2. Nucleoside
3. Nucleotide
4. Purine

3. **Analyzing Each Option**:
- **Pyrimidine**: This refers to a class of nitrogenous bases that includes cytosine, thymine, and uracil. Since uridine contains uracil, it can be classified as a pyrimidine.
- **Nucleoside**: Uridine is indeed a nucleoside as it consists of a nitrogen base (uracil) and a sugar (ribose).
- **Nucleotide**: A nucleotide consists of a nucleoside plus a phosphate group. Uridine itself does not contain a phosphate group, so it is not classified as a nucleotide.
- **Purine**: Purines are another class of nitrogenous bases that include adenine and guanine. Uridine does not belong to this category.

4. **Conclusion**:
- The correct classification of uridine, which is present only in RNA, is that it is a **nucleoside**. However, since the question emphasizes the presence of uracil, it can also be classified as a **pyrimidine**. But the most direct answer to the question is that uridine is a **nucleoside**.

### Final Answer:
Uridine, present only in RNA, is a **nucleoside**.