What trend should a graph of enzyme activity show with increased substrate concentration?

With increased substrate concentration, a graph of enzyme activity typically exhibits an increase in the rate of reaction followed by leveling off. This pattern occurs because, at low substrate concentrations, more substrate molecules are available for the enzyme to bind, resulting in an increase in product formation as the enzyme works more efficiently.

However, as substrate concentration continues to increase, the enzymes begin to become fully saturated with substrate. Once all active sites of the available enzyme molecules are occupied, any additional substrate will not further increase the reaction rate. This saturation point leads to a plateau on the graph, where the rate of product formation levels off, indicating that the enzyme is working at its maximum capacity. Therefore, the correct response accurately reflects this characteristic behavior of enzymatic reactions in relation to substrate concentration.