Glucose is reabsorbed by cells lining a kidney tubule so that it is not lost in the urine.
A student investigated the movement of glucose across the cell membranes of kidney tubule cells.
The cells in tests 1 and 2 had the same surface area and were kept at the same temperature.
| Test | Glucose concentration outside the cells / mmol/dm³ | Glucose concentration inside the cells / mmol/dm³ |
|---|---|---|
| 1 | 7.0 | 5.0 |
| 2 | 11.0 | 5.0 |
Compare the expected rates of diffusion of glucose into the cells in tests 1 and 2.
In tests 3 and 4, the glucose concentration outside the cells was 2.0 mmol/dm³ and the glucose concentration inside the cells was 5.0 mmol/dm³.
| Test | Respiration rate / % of rate in test 3 | Glucose uptake rate / µmol per gram per minute |
|---|---|---|
| 3 | 100 | 0.80 |
| 4 | 25 | 0.20 |
Explain how the results show that glucose uptake involves active transport.
Predict the glucose uptake rate if respiration stopped completely.
140 exam-style questions on AQA GCSE Biology 1.3 Transport in cells, covering 1.3.1 Diffusion, 1.3.2 Osmosis, and 1.3.3 Active transport. Each one has a worked solution and a mark scheme showing where the marks go.