The bases of nucleic acids are purines or pyrimidines.Which statement contrasting purines and pyrimidines is true?
A) Purines include the bases cytosine and thymine, whereas pyrimidines include the bases adenine and guanine.
B) Pyrimidines are found in RNA, whereas purines are found in DNA.
C) Purines are double-ring structures, whereas pyrimidines are single-ring structures.
D) Purines have only single bonds in their structure, whereas pyrimidines have both single and double bonds in their structure.
E) Purines consist of hydrogen, carbon, oxygen, and nitrogen, whereas pyrimidines have phosphorus, hydrogen, carbon, oxygen, and nitrogen.

Question

Quizplus · Accepted Answer

Purines are double-ring structures, whereas pyrimidines are single-ring structures. All the other options are incorrect. A is incorrect because cytosine and thymine are pyrimidines, whereas adenine and guanine are purines. B is incorrect because both DNA and RNA contain both purines and pyrimidines. D is incorrect because purines have both single and double bonds in their structure, whereas pyrimidines have only single bonds. Finally, E is incorrect because both purines and pyrimidines contain hydrogen, carbon, oxygen, and nitrogen, but only purines contain phosphorus.

The Bases of Nucleic Acids Are Purines or Pyrimidines