An enzyme found inside a human cell ____.

A) can catalyze many different reactions by binding to various substrates
B) helps bring reactants to the transition state
C) can catalyze endergonic reactions only
D) rarely requires cofactors
E) works optimally at temperatures below 37^oC

The role of enzymes is to bring reactants to the transition state, which lowers the activation energy required for the reaction to occur. Enzymes are specific for particular substrates, so they do not catalyze many different reactions. Enzymes can catalyze both exergonic and endergonic reactions. Enzymes often require cofactors or coenzymes to function properly. While some enzymes may work optimally at temperatures below 37°C, this is not a general characteristic of all enzymes.