Final answer:
Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy. They are specific to the substrate they act on and are usually complex proteins.
Step-by-step explanation:
Enzymes are biological catalysts that speed up chemical reactions. They are named enzymes, not ferments, catalysts, activators, or accelerators. They are usually complex proteins and are specific to the substrate they act on. Enzymes lower the activation energy of reactions, allowing them to occur more quickly.