Figure 6.2 Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme held constant.
-In Figure 6.2, 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

Figure 6.2 Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme held constant.
-In Figure 6.2, 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 enzyme molecules are already occupied by substrate. Therefore, increasing the substrate concentration further does not increase the rate of the reaction since there are not many free enzyme molecules left to bind with the additional substrate. This leads to a plateau in reaction rate.

Figure 62 Rate of an Enzyme-Catalyzed Reaction as a Function of of Varying