Digestive Enzymes and Bile

IGCSE Edexcel Biology
2.29-2.31 Digestive Enzymes and Bile
Key Concept: Enzymes break large food molecules into small soluble products, and bile helps lipid digestion.

Section A: Enzymes

1. Match each enzyme to its substrate and product. [3]

a) Amylase

b) Protease

c) Lipase

2. State where amylase and protease are produced (one organ each). [2]

Section B: Bile

3. State two roles of bile in digestion. [2]
4. Explain how emulsification helps lipase work. [2]

Section C: Digestion

5. Describe what happens to starch in the small intestine. [2]
Total marks: 11

Mark Scheme

1. Amylase: starch to maltose/glucose; Protease: proteins to amino acids; Lipase: lipids to fatty acids and glycerol [3]
2. Amylase: salivary glands or pancreas; Protease: stomach or pancreas (one each) [2]
3. Neutralises stomach acid; emulsifies lipids [2]
4. Emulsification increases surface area of lipid droplets so lipase works faster [2]
5. Starch is broken down by amylase to maltose/glucose, which can be absorbed [2]