Large food molecules need to be broken down through digestion to allow for absorption and assimilation of nutrients. Digestion is made possible by enzymes, which are protein catalysts that break down substrates into products. The three main enzymes involved in digestion are amylase, protease, and lipase. Amylase breaks down starches into sugars in the small intestine, protease breaks down proteins into amino acids, and lipase breaks down fats into fatty acids and glycerol. The digestive system includes the mouth, esophagus, stomach, small intestine, and large intestine, each playing an important role in the multi-step process of breaking down food and absorbing nutrients.

1. Digestion (Core)
Stephen Taylor
i-Biology.net

2. Assessment Statements Obj.
6.1.1 Explain why digestion of large food molecules is essential. 3
6.1.2 Explain the need for enzymes in digestion. 3
State the source, substrate, products and optimum pH conditions for one
6.1.3 1
amylase, one protease and one lipase.
6.1.4 Draw and label a diagram of the digestive system. 1
6.1.5 Outline the functions of the stomach, small intestine and large intestine. 2
6.1.6 Distinguish between absorption and assimilation. 2
Explain how the structure of the villus is related to its role in absorption and
6.1.7 3
transport of products of digestion.
What connections can you make with other topics?
Digestion
Command terms: http://i-biology.net/ibdpbio/command-terms/ Assessment statements from: Online IB Biology Subject Guide

4. Enzymes review:
• What type of biological molecule is an enzyme?
• How do enzymes work?
• How are enzymes produced through protein synthesis?
• What are the effects of temperature, pH and substrate
concentration on the rate of enzyme activity?
• How are immobilized enzymes used in the production of lactose-
free milk?

5. http://www.northland.cc.mn.us/biology/biology1111/animations/enzyme.html

8. http://highered.mcgraw-
hill.com/sites/0072495855/student_view0/chapter26/animation__organs_of_digestion.html

18. @IBiologyStephen
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