A student investigated the effect of membrane surface area on the rate of diffusion of glucose.
The student made four bags from the same partially permeable membrane. The bags had different surface areas but each contained the same volume and concentration of glucose solution. The thickness of the membrane was the same for every bag.
Each bag was placed in the same volume of water for 10 minutes. The temperature was kept constant. The student calculated the rate at which glucose diffused out of each bag. The student carried out three tests at each surface area.
| Surface area of membrane in cm² | Rate of diffusion in mg per minute: test 1 | Rate of diffusion in mg per minute: test 2 | Rate of diffusion in mg per minute: test 3 |
|---|---|---|---|
| 25 | 0.40 | 0.44 | 0.41 |
| 50 | 0.77 | 0.81 | 0.79 |
| 75 | 1.10 | 1.18 | 1.14 |
| 100 | 1.46 | 1.52 | 1.49 |
The student concluded that increasing the surface area of a membrane increases the rate of diffusion through the membrane.
Evaluate how convincing the evidence is for the student's conclusion.
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.