Which of the following statements is incorrect about enzyme catalysis?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Enzymes are highly reactive at high temperature
Enzymes are protein molecules that act as biological catalysts. Their activity depends on the shape of the protein, which is held by weak forces. Each enzyme works best at an optimum temperature; at a high temperature the protein is denatured, its shape is lost and its activity falls.
Option (1) Enzymes are mostly proteinaceous in nature — A correct statement about enzyme catalysis. Almost all enzymes are globular proteins.
Option (2) Enzyme action is specific — A correct statement about enzyme catalysis. An enzyme catalyses one particular reaction; urease, for example, catalyses the hydrolysis of urea only.
Option (3) Enzymes are denatured in ultraviolet rays. — A correct statement about enzyme catalysis. Like heat, ultraviolet radiation disturbs the structure of the protein and destroys enzyme activity.
Option (4) Enzymes are highly reactive at high temperature — Not a correct statement about enzyme catalysis. Enzyme activity is highest at the optimum temperature (298-310 K) and falls on either side of it. At a high temperature the enzyme is denatured, so it is not highly reactive.
NCERT (Pre-rationalised edition, 2022-23):
Characteristics of Enzyme Catalysis – …
