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 compare simple diffusion, facilitated diffusion and active transport by direction, energy use and the proteins involved. (Guide: “Three ways across the membrane”)
- I can explain why active transport needs both a membrane protein and a direct input of metabolic energy such as ATP. (Guide: “Three ways across the membrane”; Practice Q5)
- I can describe the steps of the sodium–potassium pump cycle, including where ATP and phosphorylation come in. (Guide: “The sodium–potassium pump”; Figure 1; Practice Q1)
- I can explain what an electrochemical gradient is and why Na⁺ rushes into a resting cell when its channels open. (Guide: “Electrochemical gradients and membrane potential”; Practice Q3)
- I can explain how the pump helps maintain the membrane potential, directly and by keeping the ion gradients. (Guide: “Electrochemical gradients and membrane potential”; Practice Q4)
- I can give examples of other pumps, such as proton and calcium pumps, and say what each one maintains. (Guide: “Electrochemical gradients and membrane potential”; Practice Q5, Q6)
Calculation and skills
- I can use the 3 Na⁺ : 2 K⁺ : 1 ATP ratio to calculate ion movement, ATP use and net charge moved. (Guide: Worked examples 1 and 2; Practice Q2, Q7)
- I can calculate concentration ratios across a membrane, including from pH values. (Guide: Worked example 2; Practice Q5, Q6)
- I can describe a graph of membrane potential over time, using numbers for each phase. (Practice Q4)
Reasoning
- I can use the concentration push and the electrical push together to predict which way an ion leaks. (Guide: Worked example 2; Practice Q3, Q6)
- I can predict the effects of stopping a pump on ion gradients, membrane potential, pH or cell volume. (Guide: Worked example 1; Practice Q4, Q5)
- I can explain why cells must keep spending ATP to maintain gradients. (Guide: Worked example 2; Practice Q6)
All ticked? Move on to Topic 2.9, Cell Compartmentalization, or return to the course roadmap.