Which one of the following pairs of nitrogenous bases of nucleic acids is wrongly matched with category mentioned against it?

Options

A. Guanine, adenine — purines
B. Adenine, thymine — purines
C. Thymine, uracil — pyrimidines
D. Uracil, cytosine — pyrimidines

Answer

To solve the question of which pair of nitrogenous bases of nucleic acids is wrongly matched with the category mentioned against it, we can follow these steps:

### Step-by-Step Solution

1. **Understand the Categories of Nitrogenous Bases**:
- Nitrogenous bases are classified into two categories: **Purines** and **Pyrimidines**.
- **Purines** include:
- Adenine (A)
- Guanine (G)
- **Pyrimidines** include:
- Thymine (T)
- Uracil (U)
- Cytosine (C)

2. **Analyze the Options**:
- We need to evaluate each option provided to identify if the bases are correctly classified into Purines or Pyrimidines.

3. **Evaluate Each Option**:
- **Option A**: Purines: Guanine and Adenine
- This is correct as both Guanine and Adenine are purines.
- **Option B**: Purines: Adenine and Thymine
- This is incorrect because Thymine is a pyrimidine, not a purine.
- **Option C**: Pyrimidines: Thymine and Uracil
- This is correct as both Thymine and Uracil are pyrimidines.
- **Option D**: Pyrimidines: Uracil and Cytosine
- This is also correct as both Uracil and Cytosine are pyrimidines.

4. **Identify the Wrongly Matched Pair**:
- From the evaluation, the only wrongly matched pair is **Option B** (Adenine and Thymine), where Thymine is incorrectly categorized as a purine.

5. **Conclusion**:
- The answer to the question is **Option B**.