DNA and RNA do not differ from each other in which of the following
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Nature of the backbone
DNA and RNA are both nucleic acids: chains of nucleotides, each made of a pentose sugar, a phosphate group and a nitrogenous base. In both, the nucleotides are joined by phosphodiester links between C-5′ of one sugar and C-3′ of the next, so the backbone is an alternating sugar-phosphate chain in both, with the bases attached to the sugars.
They differ in the sugar used, in one of the bases and in their structure, but the type of backbone is the same.
Option (1) Nature of sugar — DNA and RNA differ in this. DNA contains 2-deoxyribose, RNA contains ribose; they differ.
Option (2) Nature of the nitrogenous bases — DNA and RNA differ in this. Both have adenine, guanine and cytosine, but the fourth base is thymine in DNA and uracil in RNA; they differ.
Option (3) Nature of the backbone — DNA and RNA do not differ in this. Both have a sugar-phosphate backbone joined by phosphodiester links.
Option (4) Secondary structure — DNA and RNA differ in this. DNA is a double helix of two strands, while RNA is usually a single strand; they differ.
NCERT (2026-27 edition):
Chemical Composition of Nucleic Acids – “Complete hydrolysis of DNA (or RNA) yields a pentose sugar, phosphoric acid and nitrogen containing heterocyclic compounds (called bases). In DNA molecules, the sugar moiety is β-D-2-deoxyribose whereas in RNA molecule, it is β-D-ribose. DNA contains four bases viz. adenine (A), guanine (G), cytosine (C) and thymine (T). RNA also contains four bases, the first three bases are same as in DNA but the fourth one is uracil (U).”