Which of the following is not the characteristic of enzymes?

The correct answer is Option (1) → Non-specific

Enzymes are biological catalysts, almost all globular proteins. They are highly specific: each enzyme catalyses one particular reaction of one particular substrate. Being “non-specific” is the opposite of how enzymes behave.

• Option (1) Non-specific — Not a characteristic of enzymes. Urease, for example, hydrolyses only urea and no other amide.

• Option (2) Activate at optimum pH — A characteristic of enzymes. Enzyme activity is maximum at a particular pH, the optimum pH (about 5 to 7).

• Option (3) Affected by inhibitors — A characteristic of enzymes. Inhibitors and poisons bind to an enzyme and reduce or destroy its activity.

• Option (4) Highly efficient — A characteristic of enzymes. One enzyme molecule may transform about a million reactant molecules per minute.

NCERT (2026-27 edition):
Enzymes – “Life is possible due to the coordination of various chemical reactions in living organisms. An example is the digestion of food, absorption of appropriate molecules and ultimately production of energy. This process involves a sequence of reactions and all these reactions occur in the body under very mild conditions. This occurs with the help of certain biocatalysts called enzymes. Almost all the enzymes are globular proteins. Enzymes are very specific for a particular reaction and for a particular substrate.”

NCERT (Pre-rationalised edition, 2022-23):
Characteristics of Enzyme Catalysis – “… (iv) Highly active under optimum pH: The rate of an enzyme-catalysed reaction is maximum at a particular pH called optimum pH, which is between pH values 5-7. … (vi) Influence of inhibitors and poisons: Like ordinary catalysts, enzymes are also inhibited or poisoned by the presence of certain substances.”