2.2 Movement of Materials in and out of the cell

• Diffusion as a process by which materials move in and out of the cell
• Osmosis as a process by which water moves in and out of the cell
• Experiments to demonstrate diffusion and osmosis
• Importance of diffusion and osmosis in living things

• explain the process of diffusion in living things
• explain the process of osmosis in living things
• carry out experiments to demonstrate diffusion and osmosis
• appreciate the importance of diffusion and osmosis in living things

“How do materials move in and out of the cell?”

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1. How materials cross the membrane
   40 min · 1 practice tasks · quiz
   Why a cell must let some things in and some things out, and what decides which.
2. What diffusion is
   40 min · 1 practice tasks · quiz
   The spreading of particles from crowded places to less crowded ones, and why it happens by itself.
3. Diffusion in gases
   40 min · 1 practice tasks · quiz
   Why smells travel fast across a room, and how to show it without any apparatus.
4. Diffusion in liquids
   40 min · 1 practice tasks · quiz
   Colour spreading through still water, and why it takes so much longer than in air.
5. Writing up a diffusion experiment
   40 min · 1 practice tasks · quiz
   Turning what you did and saw into a report anybody else could follow and repeat.
6. What affects the rate of diffusion
   40 min · 1 practice tasks · quiz
   Five things that make diffusion faster or slower, and how living things use each one.
7. Diffusion in living things
   40 min · 1 practice tasks · quiz
   Breathing, digesting and photosynthesising all depend on the same simple spreading.
8. What osmosis is
   40 min · 1 practice tasks · quiz
   The movement of water through a partially permeable membrane, from dilute to concentrated.
9. Partially permeable membranes
   40 min · 1 practice tasks · quiz
   What the membrane is actually doing, and how visking tubing lets us copy it in the laboratory.
10. The potato osmosis experiment
    40 min · 1 practice tasks · quiz
    A hollowed potato, a sugar solution and a boiled control that proves the cells must be alive.
11. The visking tubing experiment
    40 min · 1 practice tasks · quiz
    Building an artificial cell and watching it take in water through the glass tube.
12. Osmosis in plant cells
    40 min · 1 practice tasks · quiz
    Turgid, flaccid and plasmolysed, and why a wall means a plant cell can never burst.
13. Osmosis in animal cells
    40 min · 1 practice tasks · quiz
    With no wall to push back, an animal cell bursts in water and shrivels in strong salt solution.
14. Comparing diffusion and osmosis
    40 min · 1 practice tasks · quiz
    What is the same, what is different, and how to tell which process a question is about.
15. Why diffusion and osmosis matter
    40 min · 1 practice tasks · quiz
    Root hairs, support, water balance and transport, and why nothing lives without these processes.
16. Diffusion and osmosis at home
    40 min · 1 practice tasks · quiz
    Salting fish, sugaring fruit, reviving vegetables and over-fertilising, all explained by osmosis.