The Following graph shows the effect of altering a factor on the rate of an enzyme Controlled reaction What is shown on x axis:

Explanation

Substrate concentration refers to the amount of substrate present in a chemical reaction. In simple terms, it's the concentration of the reactant that is being transformed into a product. The substrate concentration can affect the rate of a reaction. Generally, as the substrate concentration increases, the rate of the reaction also increases, up to a certain point. After reaching this point, called the saturation point, increasing the substrate concentration further does not have a significant effect on the reaction rate. This is because all the enzyme active sites are already occupied, and the reaction is occurring at its maximum rate.