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Multiple Choice
Which of the following nitrogenous bases are classified as pyrimidines?
A
Cytosine
B
Adenine
C
Guanine
D
Thymine
Verified step by step guidance
1
Understand the classification of nitrogenous bases: Nitrogenous bases are divided into two categories, purines and pyrimidines. Purines have a two-ring structure, while pyrimidines have a single-ring structure.
Identify the pyrimidines: The pyrimidines in DNA and RNA are cytosine, thymine, and uracil. In DNA, thymine is present, while in RNA, uracil replaces thymine.
Recognize the purines: Adenine and guanine are purines, characterized by their double-ring structure.
Apply this knowledge to the given options: From the list provided, cytosine and thymine are pyrimidines, while adenine and guanine are purines.
Conclude the classification: Based on the structural differences, cytosine and thymine are the correct answers for pyrimidines in the given options.