Digestive enzymesSpec 2.29
In short
Digestive enzymes break large, insoluble food molecules into small, soluble molecules that can be absorbed into the blood. Amylase breaks starch into maltose, and maltase breaks maltose into glucose. Proteases break proteins into amino acids. Lipases break lipids into fatty acids and glycerol. Each type of enzyme breaks down one type of food molecule.
Food contains large molecules of starch, protein and lipid. They are too big to pass into the blood. Digestive enzymes break them down into small, soluble molecules that can be absorbed. Each type of enzyme breaks down one type of food molecule.
| Enzyme | Breaks down | Into | Made in |
|---|---|---|---|
| Amylase | Starch | Maltose | Salivary glands, pancreas |
| Maltase | Maltose | Glucose | Small intestine |
| Proteases | Proteins | Amino acids | Stomach, pancreas, small intestine |
| Lipases | Lipids (fats and oils) | Fatty acids and glycerol | Pancreas, small intestine |
The digestion of starch takes two steps. Amylase breaks starch down into the sugar maltose. Maltase then breaks maltose down into glucose.
The small molecules are absorbed into the blood. The body uses them to make new carbohydrates, proteins and lipids. Some glucose is used in respiration.
Learn the pairs: amylase with starch, protease with protein, lipase with lipid. Mark schemes ask for the name of the enzyme and the products, so write both.
Written and checked against the Edexcel IGCSE Biology (4BI1) specification · Updated October 2026