Question

Which of the following compounds are Purines ? A. Adenine
B. Thymine
C. Cytosine
D. Guanine
Choose the correct answer from the options given below :

• A. A and C Only
• B. B and C Only
• C. B and D Only
• D. A and D Only

Hint:

Purines = A, G (double ring) ; Pyrimidines = C, T (single ring).

Answer 1

The Correct Option is D

Concept: Nitrogenous bases in DNA are classified into two groups: purines and pyrimidines. This classification is based on their chemical structure.

Step 1: Understanding Purines.
Purines are nitrogenous bases with a double-ring structure. The two purines in DNA are:
• Adenine (A)
• Guanine (G)

Step 2: Understanding Pyrimidines.
Pyrimidines have a single-ring structure and include:
• Cytosine (C)
• Thymine (T)

Step 3: Evaluating options.

• Adenine – Purine (correct)
• Thymine – Pyrimidine (incorrect)
• Cytosine – Pyrimidine (incorrect)
• Guanine – Purine (correct)

Step 4: Final evaluation.
Thus, the correct purines are Adenine and Guanine. Final Conclusion:
Hence, the correct answer is option (4).