The concentration of substrate affects the rate of enzymatic reactions according to the Michaelis-Menten kinetics. As the substrate concentration increases, the rate of the enzymatic reaction also increases, up to a certain point. This is because enzymes have a limited number of active sites where the substrate can bind. When the substrate concentration is low, there are more available active sites, and the reaction rate increases as more substrate molecules bind to the enzyme.However, as the substrate concentration continues to increase, the active sites on the enzyme become saturated, meaning that they are all occupied by substrate molecules. At this point, the reaction rate reaches its maximum velocity Vmax and will not increase further, even if more substrate is added. The reaction rate will remain constant at Vmax as long as the enzyme concentration remains constant.The relationship between substrate concentration and reaction rate can be described by the Michaelis-Menten equation:v = Vmax * [S] / Km + [S] where v is the reaction rate, Vmax is the maximum reaction rate, [S] is the substrate concentration, and Km is the Michaelis constant, which represents the substrate concentration at which the reaction rate is half of Vmax.Competitive inhibition occurs when an inhibitor molecule that resembles the substrate binds to the enzyme's active site, preventing the substrate from binding and thus slowing down the reaction rate. The inhibitor competes with the substrate for the active sites on the enzyme, hence the name "competitive inhibition."In the presence of a competitive inhibitor, the apparent Km of the enzyme increases, meaning that a higher substrate concentration is required to achieve the same reaction rate as in the absence of the inhibitor. However, the Vmax remains unchanged, as the enzyme can still reach its maximum reaction rate if enough substrate is present to outcompete the inhibitor.To overcome competitive inhibition, the substrate concentration can be increased to a level where it can effectively compete with the inhibitor for the active sites on the enzyme. This will help restore the reaction rate towards its original value in the absence of the inhibitor.