Question

Which of the following nitrogenous bases is classified as a purine with a double-ring structure?

Options

• Cytosine and Thymine

• Cytosine and Guanine

• Adenine and Guanine

• Uracil and Adenine

Answer 1

Purines have a double-ring structure and include Adenine (A) and Guanine (G), which are present in both DNA and RNA. Pyrimidines, which have a single-ring structure, include Cytosine, Thymine, and Uracil.