The graph represents the concentration of substrate on enzyme activity, where
A- Concentration of substrate
B- Vmax/2
C- Km constant
D- Velocity of reaction
With the increase in substrate concentration, the velocity of the enzymatic reaction rises at first. The reaction ultimately reaches a maximum velocity (Vmax) which is not exceeded by any further rise in the concentration of the substrate. This is because the enzyme molecules are fewer than the substrate molecules and after saturation of these molecules, there are no free enzyme molecules to bind with the additional substrate molecules.