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Question
Which of the following are purine bases?
(i) Guanine
(ii) Adenine
(iii) Thymine
(iv) Uracil
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Solution
(i) Guanine
(ii) Adenine
Explanation:
Purines consist of six-membered and five-membered nitrogen-containing ring fused together.
Guanine and adenine are purine bases whose structures are
Adenine (A)

Guanine (G)
While thymine and uracil are pyrimidine bases.
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