Name:________________________________________________
Class Period:_____________
Lab: Observing Osmosis in Gummy Bears
Purpose: To investigate the movement of water from a high concentration to a low concentration
Question: What will happen if I leave a gummy bear in water overnight in water? What will happen if I
leave a gummy bear overnight in salt water?
Background Information:
Molecules move in and out of a membrane from a high concentration to a low concentration. This
movement is called diffusion. The diffusion of water through a selectively permeable membrane is
known as osmosis. Selectively permeable means that some molecules can move through a membrane,
while others cannot.
In this lab we will investigate how water moves into and out of a gummy bear. The gummy bear is a jellylike, water-based substance. There are many ingredients dissolved into the water to make the gummy
bear the way that it is. The gummy bear will act like a cell. Remember that in order for the cell to stay in
homeostasis, the concentration inside a cell must be equal to the concentration outside the cell. We will
use plain water for one group and highly concentrated salt water for another group to observe the
movement of water.
Pre-lab Questions: Use your notes to answer.
1. Describe what a lipid bilayer is.
2. Name some of the macromolecules found in the lipid bilayer of a cell membrane and what job they
perform.
Vocabulary:
1. Concentration
2. Diffusion
3. Osmosis
4. Cell membrane
5. Selectively Permeable
6. Hypothesis: Use the terms DIFFUSE and CONCENTRATION in your hypothesis and reasoning
1. Hypothesis 1- If we place a gummy bear in water overnight, then the gummy bear will…
I think this because…
2. Hypothesis 2- If we place a gummy bear in salt water overnight, then the gummy bear will…
I think this because…
Procedure:
1. Obtain 2 plastic cups, and 2 gummy bears.
2. Label your cup with your group member names and class period.
3. Label one cup “H2O” and one cup “SALT H2O”
4. Measure the length of the gummy bear in cm. Write it here:____________________________
5. Fill the H2O cup with tap water from the sink.
6. Fill the Salt H2O cup with the concentrated salt water solution from the teacher.
7. Place one gummy bear in each cup.
8. Place your cup on the window will in the back of the room to sit overnight.
Results:
1. Remove the gummy bears from the cups and place on a paper towel.
2. Measure the length of the gummy bear in salt water and the length of the gummy bear in tap
water. Record your results below:
Gummy bear in water length (cm):_____________________
Gummy bear in salt water length (cm):_________________
Analysis:
1. What happened to the size of gummy bear that was placed in water?
2. What happened to the size of the gummy bear that was placed in salt water?
3. Describe the movement of water in the gummy bear that was placed in water.
4. Describe the movement of water in the gummy bear placed in salt water.
5. A marathon runner has just ran a 26 mile long race. She was running for over 4 hours, and it was
very hot out. The runner sweat the whole race and lost a lot of salt in her sweat. After the race, she
felt very dehydrated and drank a lot of water. Shortly after, she was rushed to the hospital and
died. Describe in terms of cell membranes, homeostasis, concentration inside and outside the cell,
and diffusion/osmosis why the runner did not survive.