Question

What is a catalyst?

Answer 1

A substance that speeds up a reaction. In life, we have proteins that are catalysts that speed up digestion and many other reactions. But they're not always proteins, they can be smaller chemical compounds.

Answer 2

It "speeds up" the reaction by lowering the activation energy needed for the reaction to happen. Going off of what Kainui was referring to, biological catalysts are called enzymes.