Answer the following question given this paragraph: Enzymes are involved in most biochemical reactions, and they do their job extremely well. A typical biochemical reaction could take several days to occur without an enzyme. With the proper enzyme, the same reaction can occur in just a split second! Without enzymes to speed up biochemical reactions, most organisms could not survive. The activities of enzymes depend on the temperature, ionic conditions, and the pH of the surroundings. Some enzymes work best at acidic pHs, while others work best in neutral environments. Q: Most organisms could not survive without what being present to speed up biochemical reactions? Choices: - vitamins - lipids - hormones - enzymes A:
enzymes