Revision- Enzymes

Enzymes break large food molecules into smaller nutrients that can be absorbed (through the intestinal walls). 

Different foods have different chemicals joined together so they need different enzymes, eg some enzymes break protein and some break lipids.

Different areas of the digestive system have different conditions (eg acidic and alkaline) so different enzymes are needed.

Digestion occurs much more quickly with enzymes.

Digestive enzymes are proteins that have special shapes with an active site that allow them to act as catalysts when food is broken down.

Each different enzyme can catalyse only one specific reaction. eg lipase can only break lipids in to glycerol and 3 fatty acids. Amylase can only break starch to maltose.

The enzymes are not used up in the reaction.

Each enzyme has an optimum environmental condition (temperature and pH) in which its activity is the highest rate.