Biology A

Diffusion and Osmosis with Gummy Bears

Purpose: To investigate the movement of water into and out of a polymer. Gummy bears are made of gelatin and sugar. Gelatin is a polymer that forms large three-dimensional matrices which give structural support to jellies and jams, and lots of other things that you use every day. You will be placing gummy bears in salt water and tap water to see diffusion take place and to see if water and salt water makes a difference.

Hypotheses:

Pre-lab Questions:

  1. What does semi – permeable mean?
  1. What is the difference between osmosis and diffusion?
  1. What happens to a cell in the following situations?

Hypotonic / Hypertonic / Isotonic
Cell Size Will…

Materials:

Biology A

2 –small beakers

Tape

2 - Gummy Bears (Walmart)

Highly saturated salt solution

Tap water

Ruler

Biology A

Procedure Day 1

  1. Get 2 gummy bears, two beakers, and a ruler.
  2. Label 1 of the beakers with your name and “tap water.” Label the other with “salt water” and your name.
  3. Measure the length, width, and height of your gummy bear to find the volume. Record in the data table.
  4. Put water in one of the beakers and salt water in the other beaker (you will have to make the salt water).
  5. Place a gummy bear in each of the beakers.
  6. Let the gummy bears sit over night.

Procedure Day 2

  1. Get your beakers and gummy bears.
  2. Take the gummy bears out of the beaker and place on a paper towel. BE CAREFUL SO THEY DO NOT FALL APART!!!
  3. Measure the length, width, and height of your gummy bear to find the volume. Record in the data table.
  4. Dump out the water and clean up.
  5. Calculate the percent change in volume after each step of the experiment. Record in the data table.

Day 1 Data Table(Use decimals!)

Length(cm) / Width(cm) / Height(cm) / Volume(cm3)
Tap Water
Saltwater

Day 2 Data Table

Length(cm) / Width(cm) / Height(cm) / Volume(cm3)
Tap Water
Saltwater

Percent Change in Volume of Gummy Bears

% change in volume = (final volume - initial volume)/ initial volume x 100

% Change
Tap Water Bear
Saltwater Bear

Conclusions:

  1. What happened to the bears when placed in tap water?Why?
  1. What happened to the bears when placed in salt water? Why?
  1. How does this relate to the terms: hypotonic, isotonic, and hypertonic solution?
  1. Write a conclusion which explains the results of this experiment using the concepts of diffusion and osmosis. Compare and contrast tap water and salt water. Include data where appropriate to explainyour results and conclusions.