Why does enzyme activity plateau as substrate
concentration increases?

Answer and Explanation:

Why does enzyme activity plateau as substrate concentration increases?

Simple. The enzyme is saturated, now all available enzyme molecules are busy processing substrates.

Unavailability of Enzymes site

Explanation:

Enzymes are protein that speeds up chemical reaction.

when the substrate concentration is low the reaction rate is low bit an increase in substrate concentration leads to an increase in reaction rate and abundant free enzyme available (E) to bind the added substrate.

When the substrate concentration is high the reaction reaches a stable/ plateau stage as the enzyme active sites become saturated with substrate (ES complex), and no free enzyme site to bind the added substrate.

Reaction plateau because there are no free enzyme site to bind to by the Subtrate this is because all the site are occupied by substrate so an increase in substrate concentration will not increase the reaction rate until there are free enzymes site to bind to by the substrate in the absence the reaction reaches plateau.