Explain the use of lactase to produce lactose-free milk

State the principal dietary sources and describe the importance of: (a) carbohydrates (b) fats and oils (c) proteins (d) vitamins, limited to C and D (e) mineral ions, limited to calcium and iron (f) fibre (roughage) (g) water

Describe enzyme action with reference to the shape of the active site of an enzyme being complementary to its substrate and the formation of products