Review for Midterm II

Review for Midterm II - Review for Midterm II Lab 8:...

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Review for Midterm II Lab 8: osmosis - Purpose for lab- To investigate why osmosis is important to living system. Why do we need it, what would happen without it? - Figures: - 8.1, 8.2- show hypertonicity on left. Hypotonicity is on right. Water will flow from hypotonic to hypertonic. - 8.4- turgid cells on left, plasmolyzed cells in hypertonic solution on right - 8.5 - shows how organisims have a narrow osmotic potential. Sea water osmoconforms, freshwater is hypotonic, salt pond is hypertonic and conserve water in organism to avoid dehydration. - X- Osmotic potential - Y- Osmotic potential of body fluids - Calculating % weight change: 100 x ((current weight- initial weight) / initial weight). This is important because if we just calculated direct weight (mussel weight: 5 mg ), making comparisons would be difficult because all weights are different. - Terminology o homeostasis o solvents - dissolving agent, most usually water o solutes - what is being dissolved o isotonic - equal concentration of solvent and solute. No water flow o hypertonic - high solute concentration, low water concentration. Cell looses weight o hypotonic - low solute concentration, high water concentration. Water will flow out of it. Animal cells will usually expand and burst, but not plant cells. o osmotic pressure - basically the energy used for osmosis to take place. The rate increases when there is a large difference between the concentrations in the two gradients. Pure water has an osmotic pressure of zero o o osmotic potential - same as osmotic pressure o tonicity- concentrations: hypertonic, hypotonic, isotonic o gradient- the concentration of the cell o turgid - Since plant cells don’t burst when they’re hypotonic, the instead fill with water. The plasma membrane is pressed against the cell wall.
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o turgid pressure - This increase in water taken on by the plant cell . Plant tissue becomes rigid. o
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This note was uploaded on 04/18/2008 for the course BIO 204 taught by Professor O'neal during the Fall '07 term at SUNY Stony Brook.

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Review for Midterm II - Review for Midterm II Lab 8:...

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