Anoncompetitive inhibitor decreases the rate of an enzyme reaction by

a) binding at the active site of the enzyme
b) changing the shape of the enzyme's active site
c) changing the free energy change of the reaction
d) acting as a coenzyme for the reaction

The answer is; B

This type of inhibitors does not bind the active site of the enzyme hence does not compete with the substrate (hence its name non-competitive inhibitors). They bind the enzyme at another site and change its conformation. The substrate may still be able to bind the active site but the efficiency of catalysis can be drastically reduced threatening life. This type of inhibition cannot be cured by increasing substrate levels.