7.6 B Chemical/Physical

A student listed how different parts of the body work to aid in the digestion of food.

Which of the following is a chemical change that occurs to the food?

• The reduction in size of food particles as food is chewed

• The movement of food to the stomach after food is swallowed

• The breakdown of molecules of food by enzymes and acid in the stomach

• None of the above

Many processes occur in the digestive system. Which process is best classified as a physical change?

• Salive converting the starch molecules in crakers into simple sugars

• Digestive enzymes breaking down proteins into smaller fragments

• Bacteria converting lactose into simple sugars in the intestines

• Teeth grinding an almond into smaller pieces in the mouth