Biology, Eighth Edition (Raven)

Chapter 48: The Digestive System

Organs of Digestion

Why do only animals have digestive systems? All organisms require the intake of carbon, water, and nutrients. However, only animals have a system of organs whose primary function is to break down and absorb nutrients. Fungi absorb material from the environment as individual molecules. Plants obtain carbon through photosynthesis and other nutrients are absorbed from the soil. Only animals ingest large particles of organic material that require substantial processing. Other organisms take in nutrients as individual molecules. Problems with Sugars This appears to be the same animation as ‘Blood Sugar Regulation in Diabetes’ earlier in this chapter.

View the animation below, then complete the quiz to test your knowledge of the concept.


1.	Involuntary muscle contractions which move a bolus through the gastrointestinal tract are called

		A)	mastication.
		B)	peristalsis.
		C)	defecation.
		D)	chime.

2.	Hydrochloric acid is secreted in the

		A)	esophagus.
		B)	stomach.
		C)	small intestine.
		D)	large intestine.

3.	Most nutrient absorption occurs in the

		A)	esophagus.
		B)	stomach.
		C)	small intestine.
		D)	large intestine.

4.	What organ produces bile?

		A)	liver
		B)	small intestine
		C)	pancreas
		D)	stomach

5.	Which of the following is the correct order for the major parts of the gastrointestinal tract?

		A)	esophagus, stomach, large intestine, small intestine, mouth
		B)	mouth, stomach, esophagus, large intestine, small intestine
		C)	mouth, small intestine, stomach, esophagus, large intestine
		D)	mouth, esophagus, stomach, small intestine, large intestine