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6.1 Digestion and absorption

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Description

Nature of science:
Use models as representations of the real world—dialysis tubing can be used to model absorption in the intestine. (1.10)
Understandings:
  • 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.
Guidance:
  • 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.
 Utilization:
  • 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

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