A nitrogenous base which is present in the structure of RNA but not in DNA is

Options

A. Uracil
B. Thymine
C. Cytosine
D. Guanine

Answer

To solve the question regarding the nitrogenous base present in RNA but not in DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components of Nucleic Acids**:
- Both DNA and RNA are nucleic acids made up of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base.

2. **Identify the Nitrogenous Bases**:
- The nitrogenous bases found in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
- The nitrogenous bases found in RNA are adenine (A), uracil (U), cytosine (C), and guanine (G).

3. **Compare the Bases**:
- Notice that thymine (T) is present in DNA, while uracil (U) is present in RNA.
- Uracil replaces thymine in the structure of RNA.

4. **Conclude the Answer**:
- Since uracil is the nitrogenous base that is found in RNA but not in DNA, the correct answer to the question is uracil.

### Final Answer:
The nitrogenous base which is present in the structure of RNA but not in DNA is **uracil**.

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