Question

Which one of the following statements is not true about enzymes ?

• A. Enzymes are non-specific for a reaction and substrate
• B. The action of enzymes is temperature and $pH$ specific
• C. Almost all enzymes are proteins
• D. Enzymes work as catalysts by lowering the activation energy of a biochemical reaction

Answer 1

The correct option is A Enzymes are non-specific for a reaction and substrate

Enzymes are mostly proteins. They function as catalysts in biochemical reactions by lowering the energy of activation.
Characteristics of Enzyme:
1. Highly specific nature
Each enzyme is specific for a given reaction.One catalyst cannot catalyse more than one reaction. Example: The enzyme urease catalyses the hydrolysis of urea only.It does not catalyse hydrolysis of any other amide.

2. Highly active under optimum temperature
The rate of an enzyme reaction becomes maximum at a definite temperature known as optimum temperature.On either side of the optimum temperature, the enzyme activity decreases.

3. Highly active under optimum pH
The rate of an enzyme-catalysed reaction is maximum at a particular pH known as optimum pH

Hence, option (b) is correct.