Nucleosides differ from nucleotides because they lack:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Phosphate group
A nucleoside is a nitrogenous base joined to a pentose sugar. When a phosphate group is added to the sugar, a nucleotide is formed. So a nucleoside lacks only the phosphate group.
(1) Sugar — Incorrect. A nucleoside does have a sugar. The base is joined to it.
(2) Nitrogenous base — Incorrect. A nucleoside does have a base, such as adenine or guanine.
(3) Phosphate group — Correct. This is the part that nucleotides have and nucleosides do not.
(4) Amino acid — Incorrect. Amino acids belong to proteins. They are not a part of any nucleic acid unit.
NCERT Extract:
Structure of Polynucleotide Chain – …
