The yeast acted as a catalyst. explain the purpose of a catalyst in a reaction

The catalyst speeds up the chemical reaction.

Explanation:

The process in which chemical reaction rate increases by addition of substance is termed as a catalyst. The chemical reaction happens faster when a catalyst is present because it gives an alternative reaction pathway with lower activation energy.

The catalyst usually forms a temporary intermediate that helps in regenerating the original catalyst in the cyclic process. Yeast when added in a mixture work as a catalyst and helps with chemical reaction.