The effect of substrate concentration on the rate of enzyme-catalyzed reactions can be described using the Michaelis-Menten equation. As the substrate concentration increases, the rate of the reaction also increases, but only up to a certain point. This is because enzymes have a limited number of active sites where the substrate can bind. When all the active sites are occupied by substrate molecules, the enzyme is said to be saturated, and the reaction rate reaches its maximum Vmax .In the presence of a competitive inhibitor, the inhibitor competes with the substrate for the active site of the enzyme. This means that the inhibitor can bind to the enzyme's active site, preventing the substrate from binding and thus slowing down the reaction rate. However, increasing the substrate concentration can overcome the effect of a competitive inhibitor, as the substrate molecules can outcompete the inhibitor for the active sites. In this case, the Vmax remains the same, but the apparent affinity of the enzyme for the substrate Km increases, meaning that a higher substrate concentration is required to reach half of the maximum reaction rate.In the case of a non-competitive inhibitor, the inhibitor binds to a different site on the enzyme allosteric site rather than the active site. This binding causes a conformational change in the enzyme, which reduces its catalytic activity. Unlike competitive inhibitors, increasing the substrate concentration cannot overcome the effect of a non-competitive inhibitor, as the inhibitor does not directly compete with the substrate for the active site. In this case, the Vmax decreases, while the Km remains the same, indicating that the enzyme's affinity for the substrate is not affected, but the overall reaction rate is reduced.In summary, substrate concentration affects the rate of enzyme-catalyzed reactions by increasing the reaction rate until the enzyme becomes saturated. The presence of a competitive inhibitor can be overcome by increasing the substrate concentration, while a non-competitive inhibitor reduces the overall reaction rate regardless of substrate concentration.