A-Levels

The inhibitor has a similar shape to the substrate and binds to the enzyme's active site. This means fewer enzyme–substrate complexes form, so the reaction rate decreases. With more substrate, more substrate molecules bind to the enzyme.

You identified competition at the active site and connected it to fewer enzyme–substrate complexes. Your final sentence implies the effect can be overcome but does not state the comparison clearly enough.

Model answerA competitive inhibitor binds reversibly at the enzyme's active site, competing with the substrate. This reduces the number of enzyme–substrate complexes and lowers the reaction rate at a given substrate concentration. Increasing substrate concentration makes substrate more likely to bind to the active site, so the inhibitor's effect is reduced. The maximum rate can still be reached.