You are presented with the quiz "For biological catalysts to maintain proper pH, what is needed to maintain proper pH?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "cells secrete acids and bases to maintain the proper pH for enzymes to work" and "enzyme mechanisms Enzymes are biological catalysts". 

So, what's the best answer to the question?


 

        secretion of acids and bases   