Chemical and Physical Changes in the Digestive System

In the mouth, food is torn into smaller pieces by the tearing, chewing, and grinding action of the teeth

• Physical Change

• Chemical Change

Answer explanation

A physical change occurs when there is a change in the size, shape, or the state of matter. In this example, the food is torn, chewed and ground into smaller pieces. The chemical composition of the food has not changed. This is an example of a physical change.

Both the esophagus and the small intestine are involved in the digestion of food. The esophagus squeezes food into the stomach by wave-like muscle contractions. Peptidase enzymes in the small intestine break food molecules into smaller molecules. Which statement best describes changes to food during digestion?

• The muscle contractions result in physical changes, while the action of the peptidase results in chemical changes.

• The muscle contractions and the action of the peptidase both result only in physical changes.

• The muscle contractions result in chemical changes, while the action of the peptidase results in physical changes.

• The muscle contractions and the action of the peptidase both result only in chemical changes.

Tags

NGSS.MS-LS1-7

NGSS.MS-PS1-2

Researchers are investigating processes that happen during digestion. Which answer choice describes only a physical change during digestion?

• F. Hydrochloric acid in the stomach breaks down proteins.

• G. Chewing in the mouth breaks food into smaller pieces.

• H. Enzymes in saliva start the digestion of starches before food is swallowed.

• J. Bacteria in the intestines covert dietary fiber into fats.

A students 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 on the digestive system. Which process is best classified as a physical change?

• F. Saliva converting the starch molecules in crackers into simple sugars.

• G. Digestive enzymes breaking down proteins into smaller fragments.

• H. Bacteria converting lactose into simple sugars in the intestines.

• J. Teeth grinding an almond into smaller pieces in the mouth.

Your stomach digests a yummy cookie with enzymes. Is this chemical or physical digestion? Is it both?

• physical

• chemical

• both

Researchers are investigating processes that happen during digestion. Which answer choice describes only a physical change during digestion?

• Hydrochloric acid in the stomach breaks down proteins

• Chewing in the mouth breaks food into small pieces

• Enzymes in saliva start the digestion of starches before food is swallowed

• Bacteria in the intestines convert dietary fiber into fats

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

Tags

NGSS.MS-LS1-7

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

• Saliva converting the starch molecules in crackers 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

If you mix two substances together and a brand-new substance is created, what type of change has occured?

• physical change

• quantitative change

• qualitative change

• chemical change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5