Osmosis/Diffusion lab
Honey I Blew up the Bear
Standard B-2.5 Explain how active, passive and facilitated transport serve to
maintain the homeostasis of the cell
Key terms: Osmosis, diffusion, concentration gradient
Diffusion Activity 1
1. Students will fill draw a diagram showing the air molecules distributed in the
classroom.
2. Instructor will spray air freshener at the front of the class.
3. Students will raise their hand as they start to smell the fragrance. The instructor
will hold a stopwatch and time as students raise their hands.
4. Students will draw the molecules of the fragrance in the room after 1, 10, 30
seconds.
Gummy Bear Activity
Part 1
1. Each student will get a gummy bear (Different color for everyone in group)
2. Students will take an initial weight and height and record it in data table
3. Students will place their gummy bear in a beaker full of distilled water
Part 2
1. The next day, students will remove and gently dry each gummy bear
2. Students will then re-measure weight and height and record it in the data table.
3. Students will analyze by answering questions on the worksheet
Tea Bag Activity
1. Instructor will show students a clear glass filled with water in front of the
classroom.
2. The instructor will place a tea bag in the water and students will observe what
happens after a minute
3. Students will record their observations in their worksheet
Students will then answer the end of activity questions
Introduction of terms
Instructor will prepare a powerpoint presentation to introduce the vocabulary
terms to what the students just observed. They will be able to explain the difference
between osmosis and diffusion and its importance in relation to a cell. The students
will also understand the terms concentration gradient and passive transport
Number:_______________________________
Pre MacMod
Gummy bear activity
1. You put a freshwater fish into salt water. Explain how the initial concentrations
of salt and water are different inside the fish than outside the fish.
2. Explain the movement or non-movement of salt and water in or out of the fish. If
you can, use the terms: osmosis, diffusion, and concentration gradient.
Name:___________________________________
Gummy Bear Lab
Part 1: Fragrance test
1. Draw in the box below how you think air molecules are distributed in this
classroom
Front of room
2. Why do you think the molecules are distributed this way?
Now, watch as your instructor sprays air freshener in front of the class. When you
can start to smell the fragrance, raise your hand. Think about how the molecules are
moving
After spray
3. Draw in the boxes below how you think the air freshener molecules are
distributed 1 second, 10 seconds and 30 seconds after it is sprayed.
After 1 second
After 10 seconds
Front of room
Front of room
After 30 seconds
Front of room
4. How do your molecule diagrams change with time after the air freshener is
sprayed? Why do you think the molecules moved that way?
5. How does the concentration of fragrance molecules in the room before spraying
compare to the concentration in the room after spraying?
Part 2: Gummy bears
Color of your gummy bear: ______________________
Take a measurement of length and weight of your gummy bear and record it in the
table.
Drop your gummy bear into the water.
The next day, CAREFULLY remove your gummy bear. Dry it then take length and
weight measurements again. Record it in the data table
Group
members
Initial
Weight (g)
Initial
Final
Length (cm) Weight (g)
Final
Shrink or
Length (cm) Grow?
1. What happened to the gummy bears?
2. Initially, how did the concentration of water in the gummy bear compare to the
concentration outside the gummy bear?
Part 3: Tea bag
Observe what happens when a tea bag is placed into a bowl of water
1. Draw a diagram with labeled arrows showing movement of molecules. Hint:
There are two different types of molecules moving
Tea
bag
Water
2. Was the concentration of water in the tea bag lower or higher than its
surroundings?
3. Was the concentration of tea molecules in the tea bag higher or lower than its
surroundings?
End of activity questions:
1. What can you conclude about the movement of water and molecules across a
membrane? Is there a pattern?
2. Physically, what will happen to a cell if it is placed into a solution that has a higher
concentration of molecules than inside the cell?
3. What will happen to a cell if it is placed into a solution that has a lower
concentration of molecules than inside the cell?
4. Do you think a cell has to do work (use energy) for water or molecules to move
across its membrane? Hint: think about the gummy bear or the tea bag
Number: ___________________________
Post Macmod
Gummy Bear Activity
The survival of the cells in our bodies depends on the balance between water uptake
and loss.
1. The diagram below shows animal cells in different concentrations of salt water.
Use arrows to show the movement of water and salt inside or outside of the animal
cell.
Cell
Cell
Cell
Explain why the water and salt molecules would move the way your arrows indicate.
In your answer, use the terms: osmosis, diffusion and concentration gradient.