Which bases are purines?

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Multiple Choice

Which bases are purines?

Explanation:
Purines are one of the two families of nitrogenous bases, defined by a two-ring structure. The purines are adenine and guanine. The other bases listed—cytosine, thymine, and uracil—belong to the pyrimidines, which have a single ring. In DNA and RNA, purines pair with pyrimidines (A pairs with T in DNA, or with U in RNA; G pairs with C). Therefore, the bases that are purines are adenine and guanine, making this choice correct. The other options mix purines with pyrimidines, or include only pyrimidines, which is why they aren’t correct.

Purines are one of the two families of nitrogenous bases, defined by a two-ring structure. The purines are adenine and guanine. The other bases listed—cytosine, thymine, and uracil—belong to the pyrimidines, which have a single ring. In DNA and RNA, purines pair with pyrimidines (A pairs with T in DNA, or with U in RNA; G pairs with C). Therefore, the bases that are purines are adenine and guanine, making this choice correct. The other options mix purines with pyrimidines, or include only pyrimidines, which is why they aren’t correct.

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