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 membrane is selectively permeable in terms of its hydrophobic interior. (Guide: “Why the hydrophobic interior decides”; Practice Q2)
- I can explain why ions are blocked by their charge, not their size. (Guide: “Why the hydrophobic interior decides”; Practice Q2, Q7)
- I can sort substances into those that cross freely (N₂, O₂, CO₂), those that cross in small amounts (H₂O, NH₃) and those that need channel or transport proteins. (Guide: Figure 1 and table; Practice Q1)
- I can name the main wall material of bacteria, fungi and plants, and say that archaea walls lack peptidoglycan. (Guide: “Cell walls”)
- I can describe the three roles of a cell wall: structure, a barrier to some substances, and protection from osmotic lysis. (Guide: “Cell walls”; Practice Q3, Q6)
Calculation and skills
- I can calculate a mean, standard deviation and standard error (SE = s ÷ √n) from repeats. (Guide: Worked example 2; Practice Q4)
- I can draw or read error bars of mean ± 2 SE and decide whether to reject or fail to reject a null hypothesis. (Guide: “Testing a hypothesis”; Figure 2; Practice Q4)
- I can compare rates given in powers of ten. (Practice Q7)
Reasoning
- I can predict whether a new substance will cross a bilayer from its size, polarity and charge, and propose how to test it. (Guide: Worked example 1; Practice Q5)
- I can explain why a plant cell becomes turgid but an animal cell bursts in pure water. (Guide: “Cell walls”; Practice Q3)
- I can use a control treatment to rule out an alternative explanation, such as direct damage instead of osmotic lysis. (Guide: Worked example 2; Practice Q4)
- I can evaluate a claim that goes beyond the data, such as confusing the wall’s role with the membrane’s. (Practice Q6)
All ticked? Move on to Topic 2.5, Membrane Transport, or return to the course roadmap.