Match the definitions with the correct terms.
1. Energy barrier to a chemical reaction
2. Molecule that lowers the activation energy of a reaction
3. Is not used up or changed during a chemical reaction
4. Location where chemical reaction takes place on an enzyme
5. Chemical reactant that binds to the enzyme
6. Released from the enzyme at the end of the reaction

a. Product
b. Activation energy
c. Substrate
d. Active site
e. Enzyme