Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain why a cell’s supply depends on its surface area but its demand depends on its volume. (Guide: “Why can’t a cell just keep growing?”)
- I can explain why SA/V falls as a cell grows, using how area and volume scale with length. (Guide: “How SA/V changes with size”; Practice Q1)
- I can explain how small size, flat or long shapes and membrane folds (microvilli, root hairs, cristae) keep exchange fast enough. (Guide: “Ways to keep SA/V high”; Practice Q5)
- I can explain why larger organisms exchange heat more slowly per unit mass and have a lower metabolic rate per unit body mass. (Guide: “From cells to whole organisms”; Practice Q3)
Calculation and skills
- I can calculate SA, V and SA/V for cubes and spheres, and use the shortcuts 6/s and 3/r, with units. (Guide: Worked example 1; Practice Q4)
- I can calculate SA and V for cylinders and rectangular solids, including both ends of a cylinder. (Guide: Worked example 2; Practice Q2, Q7)
- I can use a supply-and-demand model to find the largest size a cell can reach. (Guide: Worked example 1 (c); Practice Q7)
- I can calculate metabolic rate per unit mass from whole-body data. (Practice Q6)
Reasoning
- I can use a diffusion model to explain why a small cube is supplied more completely, and state how the model differs from a real cell. (Practice Q4)
- I can design a controlled experiment on how a surface feature affects uptake, standardising the measurement fairly. (Practice Q5)
- I can distinguish total rate from rate per unit mass when evaluating a claim. (Practice Q6)
All ticked? Move on to Topic 2.3, Plasma Membrane, or return to the course roadmap.