Rate of an enzyme-catalyzed reaction as a function of varying reactant
concentration, with the concentration of enzyme constant.
-In the figure, why does the reaction rate plateau at higher reactant concentrations?
A) Feedback inhibition by product occurs at high reactant concentrations.
B) Most enzyme molecules are occupied by substrate at high reactant concentrations.
C) The reaction nears equilibrium at high reactant concentrations.
D) The activation energy for the reaction increases with reactant concentration.
E) The rate of the reverse reaction increases with reactant concentration.

Question

Rate of an enzyme-catalyzed reaction as a function of varying reactant
concentration, with the concentration of enzyme constant.
-In the figure, why does the reaction rate plateau at higher reactant concentrations?
A) Feedback inhibition by product occurs at high reactant concentrations. 
B) Most enzyme molecules are occupied by substrate at high reactant concentrations. 
C) The reaction nears equilibrium at high reactant concentrations. 
D) The activation energy for the reaction increases with reactant concentration. 
E) The rate of the reverse reaction increases with reactant concentration.

Quizplus · Accepted Answer

At high reactant concentrations, most of the enzyme molecules are occupied or bound by the substrate, resulting in a plateau in the reaction rate. This is because the enzyme becomes saturated with substrate molecules and cannot work any faster, regardless of the additional substrate concentration. This is known as enzyme saturation or maximum velocity (Vmax) of the reaction. Other options such as feedback inhibition, near-equilibrium, activation energy, or reverse reaction are not directly related to the plateau in the reaction rate as a function of substrate concentration.

Rate of an Enzyme-Catalyzed Reaction as a Function of Varying