Potato & Gummy Bears Osmosis/Diffusion Lab
A shipwrecked sailor is stranded on a small deserted island with no fresh water to drink. She knows
she could last without food for up to a month, but if she didn’t have water to drink, she would be dead
within a week. Hoping to postpone the inevitable, her thirst drove her to drink the salty seawater. She
was dead in two days. Why do you think drinking seawater killed the sailor faster than not drinking any
water at all? Today we explore the cause of the sailor’s death. We’ll use a salt water solution to
represent the sea, and we’ll use cubes cut out potatoes and gummy bears to represent the sailor.
Potatoes are made of cells, as is the sailor!
Purpose:
The concentration of solute in a solution will affect the movement of water across potato cell
membranes and gummy bears.
Materials:
Potato, razor blade, 6 small plastic cups, 3 gummy bears of different colors, tape and marker for
labeling, distilled water, sugar solution, salt solution, electronic balance, metric ruler, plastic wrap, 2
plastic weighing cups.
Procedure:
Potato Lab:
1. Cut a chunk of potato into 3 cubes that are 1 cm x 1cm x 1cm.
2. Weigh each potato cube on the electronic scale using another small plastic cup to hold it. Place
the small plastic cup on the scale. Press Tare. Then place the potato cube inside. Record the
mass(g) in table.
3. Pour the following solutions into its own labeled plastic cup: distilled water ( A) , salt water
solution( B) , sugar water solution( C) .
4. Place each potato cube into one of the solutions ( A, B, C).
5. Leave potatoes in solution overnight.
Next class:
6. Remove each potato from solution. Blot the excess water off each potato.
7. Weigh each potato cube on the electronic scale using the small plastic cup/Tare method
described in number 2. Record the mass (g), length, and appearance in the table.
Gummy Bear Lab:
1. Weigh a gummy bear on the electronic scale using a small plastic cup to hold it. Place the small
plastic cup on the scale. Press Tare. Then place the gummy bear inside. Record the mass(g) in
the table.
2. Pour the following solutions into its own labeled plastic cup: distilled water ( A) , salt water
solution( B) , sugar water solution( C) .
3. Place each gummy bear into one for solutions ( A, B, C).
4. Leave the gummy bears overnight.
Next Class:
5. Weigh each gummy bear on the electronic scale using the small plastic cup/Tare method
described in number 2. Record the mass (g) and appearance in the table.
Data:
Potato Osmosis Table
Solution Initial
Length(
cm)
DAY 1
Final
Length(
cm)
DAY 2
Change
in
length
( cm)
Initial
Mass
(g)
DAY 1
Final
Mass
(g)
DAY
2
Change
in Mass
( g)
Tonicity of Solution(
iso-, hypo-, or
hypertonic)
distilled
Water
Salt
Sugar
Gummy Bears Diffusion Table
Solution
Distilled
water
Salt
Sugar
Initial
Length(
cm) DAY 1
Final
Length(
cm) DAY 2
Change in
length (
cm)
Initial
Mass (g)
DAY 1
Final
Mass ( g)
DAY 2
Final
Appearance
Tonicity of
Solution(
iso-, hypo-,
hypertonic)
Results & Conclusions:
1) Make a sketch of your potato cube in the distilled water and use arrows to show the direction of
water movement across the potato cell membranes.
2) What type of solutions were the salt & sugar solutions in the potato lab? Explain how you knew
this.
3) Which solution served as the control for both experiments & why?
4) In which solutions was there a greater solute concentration outside of the potato cells?
5) In which direction did water move through these cell membranes ( see # 4)?
6) In what type of solution do plant cells do best & why?
7) In which solution, did the gummy bears experience the greatest change in mass/appearance?
8) Draw the direction of water flow in the hypertonic solution for the gummy bear experiment.
9) Did any solutes appear to diffuse in the gummy bear experiment? If so, which ones? (use all of
your senses except taste).
10) Using the information you’ve discovered from this experiment, explain why the sailor that drank
the saltwater died.