Today, we examined a case of osmosis - the diffusion of water across the cell membrane. We noted that red onion cells shriveled when placed in water (this shriveling of cell is officially called plasmolysis, and it's the same phenomena that makes your mouth dry when you eat a salty snack and your skin wrinkle when you jump into the ocean). We inferred that water must have left the cell, traveling along its concentration gradient to create an equilibrium of solute concentration inside and out of the cell.
That's the key thing about osmosis: water will move toward areas of high solute concentration. Think of it as a balancing act - the high concentration needs to be balanced out by adding extra water (like diluting Kool Aid).
Homework
R4 - mini-quiz on membranes (2.4); also, please research the "missing piece" I gave you and bring in something to share on Monday.
R6 - complete all pre-lab questions on looseleaf or in your journal. If you lost it, the lab handout can be found here:
Lab 1 - Determining the Concentration of the Cytoplasm
In order to help you with this, you should read textbook pages 89-91 about osmosis and consult the following web resources:
Osmosis Animation (from class - but it's longer)
Similar Osmosis Student Lab (may be a springboard for your ideas)
Please e-mail me with questions at MagisterHill@gmail.com
Unit test next Thursday!
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