The activity of catalase is high at higher concentration of hydrogen peroxide (substrate) present in the reaction.
Catalase is an enzyme found in living organism that catalyzes the breakdown of hydrogen peroxide to water and oxygen gas. It also protects the living cell from oxidative damage by reactive oxygen spices. However, the activity of catalase is high at higher concentration of hydrogen peroxide (substrate) present in the reaction and less time is needed for the reaction to occur.