Enzyme saturation occurs when substrate levels are so high that all enzyme molecules are actively engaged in the chemical reaction, and so further increases in substrate concentration do not increase reaction rate.

True.

Explanation:

Enzymes are protein molecules which are capable of catalyzing at least one kind of reaction.

Enzyme saturation is the point at which, the rate of reaction reaches maximum with no further increase at a particular substrate concentration.

The product formation rate of any enzyme catalysed reaction depends on the enzyme concentration as well as on the substrate concentration. The picture below shows the behaviour of their concentration using the Michaelis–Menten kinetics.