Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the 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 regarding which pair of nitrogenous bases of nucleic acids is wrongly matched with the category mentioned, we will follow these steps:

### Step 1: Understand the Types of Nitrogenous Bases
Nitrogenous bases are categorized into two main types: purines and pyrimidines.
- **Purines**: These consist of a nine-membered double-ring structure. The two main purines are adenine (A) and guanine (G).
- **Pyrimidines**: These have a six-membered single-ring structure. The main pyrimidines are cytosine (C), thymine (T), and uracil (U).

### Step 2: Analyze the Given Options
The options provided are:
1. Guanine, Adenine - Purines
2. Adenine, Thymine - Purines
3. Thymine, Uracil - Pyrimidines
4. Uracil, Cytosine - Pyrimidines

### Step 3: Check Each Pair Against Their Categories
1. **Guanine, Adenine**: Both are purines. This is correctly matched.
2. **Adenine, Thymine**: Adenine is a purine, but thymine is a pyrimidine. This is wrongly matched.
3. **Thymine, Uracil**: Both are pyrimidines. This is correctly matched.
4. **Uracil, Cytosine**: Both are pyrimidines. This is correctly matched.

### Step 4: Identify the Wrong Match
From the analysis, the pair that is wrongly matched is **Adenine, Thymine** because it incorrectly categorizes thymine as a purine when it is actually a pyrimidine.

### Conclusion
The answer to the question is **Adenine, Thymine** (Option B) as it is the wrongly matched pair.

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