A student investigates the digestion of starch, protein and lipid in two test tubes. Each tube contains equal amounts of starch, protein and lipid, and equal amounts of amylase, protease and lipase. Both tubes are kept at 37 °C and pH 8. Bile is added to tube 1 but not to tube 2. After 15 minutes, the student measures the amounts of products formed.
| Tube | Bile added | Simple sugar produced / mmol | Amino acids produced / mmol | Fatty acids produced / mmol |
|---|---|---|---|---|
| 1 | Yes | 12 | 9 | 20 |
| 2 | No | 12 | 9 | 8 |
Explain the results in the table.
The student then sets up tube 2 again, still without bile, and leaves it for 60 minutes instead of 15 minutes. Predict how the amount of fatty acids produced would compare with the result for tube 2 in the table, and explain your prediction.
304 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.