What is the connection between cells
and…
Desalination plant –Middle East
Converts salt water into fresh water
Snowboarding
parka shell and
snow pants
Dialysis machine
What variables affect the passage of
molecules through cell membranes?
Draw a cross section of a “typical”
cell membrane.
Objective
• Determine which solution is Isotonic,
Hypotonic, Hypertonic
……but you can only test 2 of the 3
solutions
Materials
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Distilled water (100% H20)
3 mystery solutions
Quadruple beam balances
Potatoes cells
IKI solution (Lugol’s solution)
Some chemistry terms used
• Solutions can be solids dissolved in liquids. They
could also be gases dissolved in liquids (such as
carbonated water).
• There can also be gases in other gases and liquids in
liquids. If you mix things up and they stay at an even
distribution, it is a solution.
• A simple solution is basically two substances that are
going to be combined. One of them is called the
solute. A solute is the substance to be dissolved
(sugar). The other is a solvent. The solvent is the
one doing the dissolving (water). As a rule of
thumb, there is usually more solvent than solute.
Homework
• Speculate on the possible effects of molecular
concentration on movement through cell
membranes. Using a model cell- design an
experiment or experiments to test your ideas.
Construct a pre-lab flowchart for your
experimental design.
Day of Lab
• After your pre-lab flowchart has been stamped off for
completion, decide as a group the different
experiments that you will run to test your hypotheses.
• Professional points will be lost for groups who do not
clean up their stations
• Record all of your results. Graph your quantitative
data and be ready to present your findings to the class
in 30 minutes.
• Did the class results reveal a consistent pattern? If
so, what was it?
• Which of the proposed hypotheses were supported by
the experimental findings? Explain
• Homework   complete question 11
After Lab
• Draw a cross section of your model cell
membrane. Label your diagram.
• Include this in your FDQ lab write up
solution, hypertonic,
n a mixture containing a concentration of solute in excess of the concentration of the
same solute in another mixture to which it is compared. When the two solutions are
placed on opposite sides of a permeable membrane (either artificial or natural, as with
cell membranes), the hypertonic solution attracts the solvent from the hypotonic solution,
equalizing the concentration of the solute in both. See also solution, hypotonic; solution,
isotonic; and osmosis.
solution, hypotonic,
n a mixture containing a concentration of solute that is lower than the concentration of
the same solute in another mixture to which it is compared. When two such solutions are
separated by a permeable membrane, the solvent of the hypotonic solution flows
through the membrane to the hypertonic solution, equalizing the concentration of the
solute in both. See also solution, hypertonic; solution, isotonic; and osmosis.
solution, isotonic,
n a mixture containing the same concentration of solute as another mixture to which it is
compared. When separated by a permeable membrane, osmosis does not occur. See
also solution, hypertonic; solution, hypotonic; and osmosis.