Sarah designed an experiment to investigate the effect of the surface-area-to-volume ratio of potato tissue on the rate of osmosis. She cut three different-sized cubes of potato with side lengths of 1 cm, 2 cm, and 3 cm. She recorded their initial masses, placed them in a beaker of distilled water for 2 hours, and then recorded their final masses.
The table below shows her results:
| Potato cube size in cm | Original mass in g | Final mass in g | Percentage change in mass (%) |
|---|---|---|---|
| 1×1×11 \times 1 \times 11×1×1 | 1.15 | 1.28 | 11.30 |
| 2×2×22 \times 2 \times 22×2×2 | 9.20 | 9.70 | |
| 3×3×33 \times 3 \times 33×3×3 | 31.05 | 32.10 | 3.38 |
Calculate the percentage change in mass for the 2×2×2 cm2 \times 2 \times 2\text{ cm}2×2×2 cm potato cube. Show your working and give your answer to two decimal places.
Calculate the surface area (SA), volume (Vol), and SA:Vol ratio for the 3×3×3 cm3 \times 3 \times 3\text{ cm}3×3×3 cm potato cube using the following formulae:
SA=6×(side length in cm)2 \text{SA} = 6 \times (\text{side length in cm})^2 SA=6×(side length in cm)2 Vol=(side length in cm)3 \text{Vol} = (\text{side length in cm})^3 Vol=(side length in cm)323 exam-style questions on Edexcel IGCSE Biology Movement of substances into and out of cells. Each one has a worked solution and a mark scheme showing where the marks go.