Final answer:
A catalyst is a substance that increases the rate of a chemical reaction without undergoing any change. Salivary amylase is an example of a catalyst that helps break down starch.
Step-by-step explanation:
A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any change. Catalysts help increase the rate and force at which atoms, ions, and molecules collide, increasing the probability of their valence shell electrons interacting.
One example of a catalyst is salivary amylase, an enzyme that speeds up the hydrolysis of amylose, a component of starch.