Question

A person starts to eat a hamburger. As she takes a bite and chews, an enzyme called salivary lipase helps to begin the process of fat digestion. Which of these is the BEST description of the role of enzymes in digestion?
A) Enzymes are acids that physically break down food molecules.
B) Enzymes moisten food to help teeth in the mechanical process of grinding and chewing.
C) Enzymes are proteins that speed up the process of chemically breaking down food molecules.
D) Enzymes are cells that secrete saliva and other necessary substance needed for digestion.

Answer 1

The best answer is C.

Enzymes are proteins that speed up the process of  chemically breaking  down food molecules. In other words they act as catalysyts. Catalaysts increase the rate at which chemical reactions occur without being consumed or permanently changed themselves. 

A chemical reaction is a process that converts one or more substances  known as substrates to another type of substance which is termed the product. As  a catalyst, an enzyme can repeat  the same type of reaction over and over again. Each enzyme has an active site where its specific substrate binds so that a reaction can begin to take place and continue to completion.

Answer 2

Enzymes are proteins that speed up the process of chemically breaking down food molecules.