Scientists use cubes to model organisms of different sizes.
The Table shows information about three cubes.
Table
| Length of side in cm\text{cm}cm | Surface area in cm2\text{cm}^2cm2 | Volume in cm3\text{cm}^3cm3 | Surface area : volume ratio |
|---|---|---|---|
| 1 | 6 | 1 | 6:16 : 16:1 |
| 2 | 24 | 8 | |
| 3 | 27 | 2:12 : 12:1 |
Calculate the surface area of the cube with sides of 3 cm.
Calculate the surface area : volume ratio of the cube with sides of 2 cm.
Describe how the surface area : volume ratio changes as the size of the cube increases.
An amoeba is a single-celled organism. It does not need a transport system.
Humans do need a transport system.
Explain why.
114 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.