Name: ___________________________________ Period: _____
Osmosis Demonstrations
Problem: How will solutions of various concentrations affect cells?
Data:
A. Dialysis Tubing
1. Below are two beakers for you to color in your initial observations.
a. Color the areas that contain starch yellow and the areas that contain iodine orange.
Initial observations:
BEAKER ONE
BEAKER TWO
b. Make your final observation and color the areas that contain starch yellow, the areas
that contain iodine orange, and the areas that contain starch and iodine purple.
Final observations:
BEAKER ONE
BEAKER TWO
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B. Elodea Cell
2. Draw the elodea cell in the space provided below.
a. Indicate that this is viewed under high power in the space provided for magnification
by entering 40X, 100X, or 400X.
b. Label the cell wall, cell membrane, chloroplasts, and central vacuole (do not cross
lines when labeling, use proper labeling techniques).
Initial drawing
Magnification: __________
3. Draw the saline-treated elodea cell in the space provided below.
a. Indicate that this is viewed under high power in the space provided for magnification
by entering 40X, 100X, or 400X.
b. Label the cell wall, cell membrane, chloroplasts, and central vacuole (do not cross
lines when labeling, use proper labeling techniques).
Saline-Treated drawing
Magnification: __________
4. Draw the saline-treated elodea cell in the space provided below.
a. Indicate that this is viewed under high power in the space provided for magnification
by entering 40X, 100X, or 400X.
b. Label the cell wall, cell membrane, chloroplasts, and central vacuole (do not cross
lines when labeling, use proper labeling techniques).
Distilled Water drawing
Magnification: __________
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Analysis Questions:
1. Go back to page one and review your initial and final diagrams of the dialysis tubing
results.
a. Explain what happened with Beaker One. Did the solution inside the tubing diffuse
outward across the membrane or did the solution outside the tubing diffuse into the
tubing?
b. How do you know?
c. Explain what Happened with Beaker Two. Did the solution inside the tubing diffuse
outward across the membrane or did the solution outside the tubing diffuse into the
tubing?
d. How do you know?
2. Go back and review the three drawings of the elodea cell you made on page 2 and explain
what happened to the elodea cells during this demonstration (Hint: you want to discuss
what substances moved and why, how they might have changed the appearance of the
cell, and include terms like concentration, osmosis, water, plasmolysis, and/or cytolysis).
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3. Draw a diagram to indicate the relative proportions of salt and water within the elodea
cells and outside the elodea cells when they were placed in the saline (salt) solution.
(Hint: I used a 20% saline solution) Also, use an arrow to properly indicate the direction
of osmosis (if water moved into or out of the cell).
4. Draw a diagram to indicate the relative proportions of salt and water within the elodea
cells and outside the elodea cells when the saline-treated elodea cells were placed in the
distilled water solution (Hint: distilled water is 100% water). Also, use an arrow to
properly indicate the direction of osmosis.
Application Questions: Be sure to include terms like: plasmolysis, cytolysis, turgid, and
concentration in your answers.
5. Red blood cells (and other animal cells) placed in a distilled water solution usually swell
up and burst. Why did this not happen when the elodea cells were placed in the distilled
water?
6. Why do grocery store owners spray fresh fruits and vegetables with water?
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7. Roads are sometimes salted to melt ice. What does this do to plants around the roadside
and why? Think about what happened in the lab.
8. If a shipwrecked crew drinks sea water, they will probably die. Why would this occur?
9. If a bowl of fresh strawberries is sprinkled with sugar, the berries will be covered with
juice a few minutes later. Why does this occur?
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