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Multiple Choice
Which of the following statements describe purines but not pyrimidines?
A
Purines are found only in RNA.
B
Purines include cytosine and thymine.
C
Purines have a two-ring structure.
D
Purines are smaller than pyrimidines.
Verified step by step guidance
1
Understand the basic structure of purines and pyrimidines: Purines have a two-ring structure, while pyrimidines have a single-ring structure.
Identify the nucleobases that are classified as purines: Adenine and guanine are purines, whereas cytosine, thymine, and uracil are pyrimidines.
Evaluate the statement 'Purines are found only in RNA': This is incorrect because purines (adenine and guanine) are found in both DNA and RNA.
Evaluate the statement 'Purines include cytosine and thymine': This is incorrect because cytosine and thymine are pyrimidines, not purines.
Evaluate the statement 'Purines have a two-ring structure': This is correct as purines are characterized by their two-ring structure, distinguishing them from pyrimidines.