Answer the question on the basis of passage given below:
Proteins are the polymers of about twenty different \(\alpha \)-amino acids which are linked by peptide bonds. Proteins perform various structural and dynamic functions in the organisms. Proteins which contain only \(\alpha \)-amino acids are called simple proteins. The secondary or tertiary structure of proteins gets disturbed on change of pH or temperature and they are not able to perform their functions. This is called denaturation of proteins. Enzymes are biocatalysts which speed up the reactions in biosystems. Vitamins are accessory food factors required in the diet. They are classified as fat soluble (A, D, E and K) and water soluble (B group and C). Deficiency of vitamins leads to many diseases. Nucleic acids are the polymers of nucleotides which in turn consist of a base, a pentose sugar and phosphate moiety. Nucleic acids are responsible for the transfer of characters from parents to offspring. There are two types of nucleic acids – DNA and RNA. DNA contains a five carbon sugar molecule called 2-deoxyribose whereas RNA contains ribose.
RNA and DNA differ due to presence/absence of oxygen at which carbon of sugar moiety?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2nd
A nucleotide consists of a base, a pentose sugar and a phosphate group. The two nucleic acids differ in the sugar: RNA contains β-D-ribose, and DNA contains β-D-2-deoxyribose. “2-Deoxy” means that the –OH group at carbon 2 of ribose is replaced by H: ribose has an oxygen at C-2, deoxyribose has none.
Ribose: C-2 carries H and OH
2-Deoxyribose: C-2 carries two H atoms
So RNA and DNA differ in the presence or absence of oxygen at the 2nd carbon of the sugar.
NCERT (2026-27 edition):
Chemical Composition of Nucleic Acids
