A technician divided a sample of human lipase into three equal samples. Each sample was kept at a different temperature for 10 minutes.
One portion of each sample was then mixed with 1.00 g of lipid for 5 minutes at the temperature shown in the first column.
The rest of each lipase sample was brought to 37 °C for 10 minutes. A second portion was then mixed with a fresh 1.00 g sample of lipid for 5 minutes at 37 °C.
| Temperature at which the lipase was initially kept in °C | Mass of lipid remaining after 5 minutes at the initial temperature in g | Mass of lipid remaining after 5 minutes following return to 37 °C in g |
|---|---|---|
| 5 | 0.88 | 0.22 |
| 37 | 0.20 | 0.21 |
| 70 | 0.96 | 0.93 |
Calculate how many times greater the mass of lipid broken down was for the sample initially kept at 5 °C than for the sample initially kept at 70 °C, after both samples had been brought to 37 °C.
Evaluate the conclusion: ‘The effect of changing temperature on lipase activity is always reversible.’
Explain why, after both enzyme samples had been brought to 37 °C, more lipid remained with the sample initially kept at 70 °C than with the sample initially kept at 5 °C.
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.