Final answer:
Enzymes have a unique active site that allows them to fit with only one substrate molecule.
Step-by-step explanation:
The active site of an enzyme is the place where the substrate binds.
Enzymes have a unique active site that allows them to fit with only one substrate molecule.
This is because the active site has a specific shape that can only accommodate a particular substrate.
For some enzymes, the active site follows a lock and key model, where the substrate fits exactly into the active site.
Other enzymes have an induced fit model, where the active site can make minor adjustments to accommodate the substrate.