Osmosis

Today we're going to start looking at osmosis, the next topic after diffusion.  Answer the following in your books:

1. Explain how diffusion works using the phrase 'concentration gradient'.
2. In osmosis, what particles are moving across the membrane?
3. How does water get into plant root cells?
4. Use the animation here (click on diffusion/osmosis, then play through). What is the 'aim' of both diffusion and osmosis?
5. Explain what isotonic, hypertonic and hypotopnic solutions are.  What can happen to cells bathed in hypertonic solutions?
6. What is turgor pressure? What can happen to a cell if turgor pressure is too high?
7. Explain how this celery is able to stand upwards. What conditions must occur for the water to move up through the cells of the plant?


8. If water is moving up through the plant, is the process diffusion or osmosis?



If the orange circles are solute and the smaller circles are water particles, in which direction will there be a net movement of water?

10. Define solute and solvent:
11. Play this game - if it doesn't woprk at school try it at home as it illustrates stuff we're talking about really well!
12. Extension - Apart from within organisms as part of Biology, where else can osmosis be useful?
13. Homework - This link won't work at school, but using it at home should run a java program about diffusion and osmosis. Try it out, and if it works name two situations where osmosis occurs in Biology. Even if the program doesn't work, researching this on the internet will work fine and will get you an achievement point if you bring it in next week.