(A) Enzymes enhance reaction rate by a factor of 2 to 10.

(B) Activation energy of a reaction is lowered by enzymes.

(C) Interactions between enzymes and substrates are hydrogen, ionic and hydrophobic bonds.

(D) Substrate concentration does not affect the rate of enzyme-catalyzed reactions.

Choose the correct answer from the options given below:

Correct option is B

Explanation of the Correct Option (b): (B) and (C) only
(B) Activation energy of a reaction is lowered by enzymes — CORRECT
· Enzymes act as biological catalysts.
· They provide an alternative reaction pathway with lower activation energy.
· This increases the rate of reaction without being consumed.
· This is the primary mechanism of enzyme action.
(C) Interactions between enzymes and substrates are hydrogen, ionic and hydrophobic bonds — CORRECT
· Enzyme–substrate complexes are stabilized by weak, non-covalent interactions, such as:
· Hydrogen bonds
· Ionic (electrostatic) bonds
· Hydrophobic interactions
· These interactions ensure specificity and reversibility of enzyme action.
Explanation of Other Statements / Options
(A) Enzymes enhance reaction rate by a factor of 2 to 10 — INCORRECT
· Enzymes can increase reaction rates by 10⁶ to 10¹² times, not merely 2–10.
· Hence, statement (A) is false.
(D) Substrate concentration does not affect the rate of enzyme-catalyzed reactions — INCORRECT
· At low substrate concentration, reaction rate increases with substrate concentration.
· Only at enzyme saturation does the rate become independent of substrate concentration.
· Therefore, statement (D) is false.
Option (a): (A) and (B) only
· Incorrect because statement (A) is false.
Option (c): (A) and (C) only
· Incorrect because statement (A) is false.
Option (d): (A) and (D) only
· Incorrect because both (A) and (D) are false.
Key Points Related to the Question
· Enzymes lower activation energy, not ΔG.
· Enzyme–substrate binding involves weak non-covalent forces.
· Reaction rate depends on substrate concentration (Michaelis–Menten kinetics).
· Enzymes are highly efficient biological catalysts.