Which statement about enzyme-catalyzed reactions is FALSE? A. At saturating levels of substrate, the rate of an enzyme-catalyzed reaction is proportional to the enzyme concentration. B. If enough substrate is added, the normal Vmax of a reaction can be attained even in the presence of a competitive inhibitor. C. The Michaelis-Menten constant Km equals the [S] at which V = 1/2 Vmax. D. The rate of a reaction decreases steadily with time as substrate is depleted. E. The activation energy for the catalyze