Identify the incorrect statement with reference to biomolecules.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Enzymes can catalyze any biochemical reactions.
Enzymes are biological catalysts, almost all of them globular proteins.
Option (1) In a β-pleated sheet structure, all peptide chains are stretched out to maximum extension and then laid side by side, which are held together by inter-molecular hydrogen bonding. — Correct about biomolecules. This is the β-pleated sheet secondary structure; the side-by-side chains look like the folds of a pleated fabric.
Option (2) In fibrous proteins, the parallel polypeptide chains are held together by hydrogen and disulphide bonds. — Correct about biomolecules. These bonds give fibrous proteins such as keratin and myosin their fibre-like, water-insoluble structure.
Option (3) Enzymes can catalyze any biochemical reactions. — Incorrect about biomolecules. Enzymes are very specific: each catalyses a particular reaction of a particular substrate. Maltase, for example, hydrolyses only maltose into glucose.
Option (4) Deficiency of vitamin K increases the blood clotting time. — Correct about biomolecules. Vitamin K is needed for the clotting of blood, so its deficiency increases the blood clotting time.
NCERT (2026-27 edition):
Enzymes
