Which base is present in `RNA` but not in `DNA`?

Options

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

Answer

To determine which base is present in RNA but not in DNA, we can follow these steps:

### Step 1: Identify the nitrogenous bases in nucleic acids
Both DNA and RNA are composed of nitrogenous bases. The major nitrogenous bases are:
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T) - found only in DNA
- Uracil (U) - found only in RNA

### Step 2: Compare the bases in DNA and RNA
- In DNA, the bases are adenine (A), guanine (G), cytosine (C), and thymine (T).
- In RNA, the bases are adenine (A), guanine (G), cytosine (C), and uracil (U).

### Step 3: Identify the unique base in RNA
From the comparison, we can see that thymine (T) is present in DNA but not in RNA. Conversely, uracil (U) is present in RNA but not in DNA.

### Step 4: Conclusion
Thus, the base that is present in RNA but not in DNA is **uracil**.

### Final Answer
The base present in RNA but not in DNA is **Uracil**.

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