Some pharmaceutical researchers are investigating the effect of the surface area : volume ratio on the rate of dissolution of a solid drug formulation. They prepare cubic pellets of the formulation in three different sizes. The pellets are placed in separate beakers containing simulated gastric acid, and the time taken for each pellet to completely dissolve is recorded.
The table below shows the results of their investigation:
| Edge length of the cubic pellet (mm\text{mm}mm) | Surface area : volume ratio | Time to completely dissolve (seconds\text{seconds}seconds) |
|---|---|---|
| 2 | .................... | 35 |
| 4 | 3:23 : 23:2 | 110 |
| 8 | 3:43 : 43:4 | 390 |
Calculate the surface area : volume ratio for the cubic pellet with an edge length of 2 mm\text{mm}mm. Write your final ratio in its simplest integer form.
What conclusion can be made about the effect of the surface area : volume ratio on the rate of dissolution?
17 exam-style questions on OCR GCSE Biology 2.2 The challenges of size, covering 2.2.1 Exchange surfaces and surface area : volume ratio, 2.2.2 Substances transported in organisms, 2.2.3 The human circulatory system, 2.2.4 The heart and blood vessels, 2.2.5 Red blood cells and plasma, 2.2.6 Uptake of water and mineral ions by plants, 2.2.7 Transpiration and translocation, 2.2.8 Xylem and phloem, 2.2.9 Environmental factors and water uptake, and 2.2.10 Using a potometer. Each one has a worked solution and a mark scheme showing where the marks go.