Digestion and absorption

Nature of science:

Use models as representations of the real world—dialysis tubing can be used to model absorption in the intestine. (1.10)

• The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.
• The pancreas secretes enzymes into the lumen of the small intestine.
• Enzymes digest most macromolecules in food into monomers in the small intestine.
• Villi increase the surface area of epithelium over which absorption is carried out.
• Villi absorb monomers formed by digestion as well as mineral ions and vitamins.
• Different methods of membrane transport are required to absorb different nutrients.

Applications and skills:

• Application: Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
• Application: Use of dialysis tubing to model absorption of digested food in the intestine.
• Skill: Production of an annotated diagram of the digestive system.
• Skill: Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph.

• Some hydrolytic enzymes have economic importance, for example amylase in production of sugars from starch and in the brewing of beer.
  • Syllabus and cross-curricular links:
  • Biology
  • Topic 2.1 Molecules to metabolism
  • Topic 2.5 Enzymes

• Students should know that amylase, lipase and an endopeptidase are secreted by the pancreas. The name trypsin and the method used to activate it are not required.
• Students should know that starch, glycogen, lipids and nucleic acids are digested into monomers and that cellulose remains undigested.
• Tissue layers should include longitudinal and circular muscles, mucosa and epithelium.