Which of the following pairs is incorrectly matched?

Options

A. Purines-Adenine and Guanine
B. Pyrimidines-Cytosine and Uracil
C. Nucleosides-Adenosine and Thymidine
D. DNA-Basic biomolecule

Explanation

To solve the question of which pair is incorrectly matched, we will analyze each option provided in the question step by step.

### Step 1: Analyze Option 1
- **Pair**: Purines are Adenine and Guanine.
- **Explanation**: Purines are indeed nitrogenous bases that include Adenine (A) and Guanine (G). This statement is correct.

### Step 2: Analyze Option 2
- **Pair**: Pyrimidines in DNA are Cytosine and Thymine.
- **Explanation**: Pyrimidines are nitrogenous bases that include Cytosine (C) and Thymine (T) in DNA. This statement is also correct.

### Step 3: Analyze Option 3
- **Pair**: Nucleosides are Adenosine and Thymidine.
- **Explanation**: Nucleosides are formed when a sugar (ribose or deoxyribose) combines with a nitrogenous base. Adenosine (from Adenine) and Thymidine (from Thymine) are indeed nucleosides. This statement is correct as well.

### Step 4: Analyze Option 4
- **Pair**: DNA is the basic biomolecule.
- **Explanation**: DNA (Deoxyribonucleic Acid) is an acidic biomolecule due to the presence of phosphate groups that release protons in solution. Therefore, this statement is incorrect.

### Conclusion
- The incorrectly matched pair is **Option 4**: DNA is the basic biomolecule.

### Final Answer
The incorrectly matched pair is: **Option 4: DNA is the basic biomolecule.**

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