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Lab Activity #2: Osmosis in Cells
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Log on to http://www.phschool.com/science/biology_place/biocoach/
Click on:
o Biomembrane I: Membrane Structure and Function 
o Concept 2: Osmosis: Movement of Water Across Membranes (on the left side of the
screen)
Osmosis (movement of water across membranes) depends on the relative concentration of solute
molecules on either side of the membrane. The presence or absence of cell walls influences how
cells respond to osmotic fluctuations in their environment.
Click on Review
Looking at the diagram above. Describe the difference between the three types of solutions.
The small circles represents dissolved solutes like salt, glucose, and amino acids. You can assume
that the additional space surrounding the solutes is water.
hypotonic - _________________________________________________________________________________
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isotonic - ___________________________________________________________________________________
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hypertonic - ________________________________________________________________________________
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Click on Next  Cells in Isotonic Solution
1. What is the concentration of salt in animal cells? _________________________
2. When cells are in isotonic solution, is there movement of water into or out of the cell? If so,
describe this movement. ____________________________________________________________________
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Click on Next  Cells in Hypotonic Solutions
Describe the net movement of water molecules when cells are placed in a hypotonic solution.
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Click on A Closer Look  A Closer Look at Plant and Animal Cells in Hypotonic Environments
**Make sure to ANIMATE the graphics.**
1. What happens to plant cells when placed in a hypotonic solution?
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2. What happens to an animal cell when placed in a hypotonic solution? (3 pts)
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3. Account for the different reactions between plant and animal cells when placed in a
hypotonic environment. ____________________________________________________________________
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4. What cell structure prevents lysis in many single-celled protists living in a fresh water
environment? ___________________________________________
Click  Back to Review then Next  Cells in Hypertonic Solutions
Describe the net movement of water molecules when cells are placed in a hypertonic solution.
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Click on A Closer Look  A Closer Look at Plant and Animal Cells in Hypertonic Environments
**Make sure to ANIMATE the graphics.**
Compare and contrast what happens to plant and animal cells when placed in a hypertonic
solution. ___________________________________________________________________________________
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