The presence or absence of hydroxyl group on which carbon in ribose sugar differentiates RNA and DNA?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 2nd
Both nucleic acids contain a pentose sugar. In RNA the sugar is β-D-ribose, which carries an –OH group on carbon 2. In DNA the sugar is β-D-2-deoxyribose: the prefix ‘2-deoxy’ means that the –OH group on carbon 2 is replaced by –H. So the presence (RNA) or absence (DNA) of the hydroxyl group on the 2nd carbon of the sugar distinguishes the two nucleic acids.
NCERT (2026-27 edition):
Chemical Composition of Nucleic Acids
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 15-06 S1 14-06 S1 | – |