Which of the following statements correctly distinguishes DNA from RNA?

• A. RNA is more stable than DNA under cellular conditions.
• B. Both DNA and RNA contain the nitrogenous base thymine.
• C. DNA is usually single-stranded, whereas RNA is usually double-stranded.
• D. DNA contains the sugar deoxyribose, while RNA contains the sugar ribose.

Answer: (D)

Verified step by step guidance

1. Understand the structural differences between DNA and RNA. DNA contains the sugar deoxyribose, which lacks an oxygen atom on the 2' carbon of the sugar ring, while RNA contains the sugar ribose, which has an oxygen atom on the 2' carbon.
2. Review the nitrogenous bases present in DNA and RNA. DNA contains thymine (T), whereas RNA contains uracil (U) instead of thymine.
3. Examine the typical structures of DNA and RNA. DNA is usually double-stranded and forms a helical structure, while RNA is typically single-stranded and can fold into various shapes.
4. Consider the stability of DNA and RNA under cellular conditions. DNA is more stable due to its double-stranded structure and the absence of the reactive hydroxyl group on the 2' carbon of deoxyribose, whereas RNA is less stable due to the presence of the hydroxyl group on ribose.
5. Conclude that the correct distinguishing feature is the type of sugar present: DNA contains deoxyribose, while RNA contains ribose.