Name _______________________________________________
Egg Osmosis Lab
Date __________________
Period ___________
Introduction:
The ability of cells to absorb water is dependent on the environment in which they are exposed to. The passive
movement of water from one cell to another requires a concentration difference across a semi-permeable membrane. We call
this movement of water from a high concentration to low concentration: osmosis.
All cells require water as the solvent in which chemical reactions that sustain life occurs. If cells are deprived of water,
these chemical reactions that slow down and ultimately stop resulting in death of that cell and perhaps the entire organism.
Therefore, one important way organisms maintain homeostasis is by attempting to insure a proper water balance in their
cells.
A chicken’s egg is surrounded by a shell. Bumpy and grainy in texture, an eggshell is covered with as many as 17,000
tiny pores. Eggshell is made almost entirely of calcium carbonate (CaCO3) crystals. It is a semi-permeable membrane, which
means that air and moisture can pass through its pores. Lying between the eggshell and egg white, the egg has an inner and
outer membrane. These two transparent semi-permeable membranes provide efficient defense against bacterial invasion
while still allowing passage of air and moisture into the actual egg. If you give these layers a tug, you’ll find they’re surprisingly
strong. They’re made partly of keratin, a protein that’s also in human hair.
Purpose:
The purpose of this activity is to learn how osmosis and the effects of hypotonic, hypertonic, and isotonic solutions on animal
cell (chicken egg).
Objectives:
The students will be able to describe osmosis and differentiate between the effects of hypotonic, hypertonic, and isotonic
solutions on animal cells (using chicken eggs).
Hypothesis (5):
Distilled Water
(Pure Water)
25% Corn Syrup
75% Water
50% Corn Syrup
50% Water
75% Corn Syrup
25% Water
100% Corn
Syrup
What type of solution
will they be defined
as? (Hypertonic,
Isotonic, Hypotonic)?
What will happen to
the cell (egg)? Shrink?
Stay the same? Or
Swell?
Water move in? Water
move out? Water
move in and out?
Pre-Lab Questions:
1. Why is an egg being used for this experiment?
2. Only the membrane of the egg is needed. How can the shell be removed without breaking the membrane (Hint, do you think
the vinegar soaking has something to do with this)?
Experiment Design:
Independent variable: ____________________________________ Dependent variable:__________________________________ Control group:
___________Eggs in Vinegar_________________________ Experimental Group: _________________________
Constants (3): _____________________________________________________________________________________________
Materials:
1 raw egg, vinegar, plastic cups, paper towels, digital balance scale, corn syrup, distilled water, tap water, beakers, stirring rod,
string
ruler, masking tape (label the cups), weight boats
Procedure: Check off each step of the procedure as you complete it.
Teacher Prep Day 1
_____1. Carefully place the raw egg into the container and cover the egg with vinegar.
_____2. Allow eggs to sit for 24 to 48 hours until the outer calcium shell is removed.
Lab Day 2
_____3. VERY carefully remove the egg from the container, GENTLY tap the egg with paper towel and place it onto a
paper towel into a weigh boat.
_____4. Describe the ‘before’ appearance (color) and shape of the egg in data table 1.
_____5. Measure the circumference size using the string (wrap the string around the width of the egg and then
measure it on the ruler) and record initial circumference for group data in data table 2.
_____6. Find the DRY mass of the egg in grams using a balance and record initial mass for group data in data table 3.
_____7. Each group will be assigned a percent of corn syrup (fructose) to dissolve in water. The assigned percentage
is the percent of corn syrup to be dissolved in final volume of 500 mL of water. For example, a 25% corn syrup
solution (of a 500 mL solution) is composed of 125 mL corn syrup and 375 mL of water.
_____8. Get a plastic cup and label the concentration of the assigned solution and everyone in the group’s names on
the masking tape.
_____9. Carefully place the egg into the cup in the freshly made corn syrup solution and let it sit for two days.
Lab Day 3
_____10. For each egg, gently remove the egg using a spoon. BE CAREFUL not to break the egg!
_____11. Place the egg onto a paper towel, gently dry off the egg using soft, dry paper towels and then place it into a
weigh boat.
_____12. Describe the ‘after’ appearance (color) and shape of the assigned egg in data table 1.
_____13. Measure the circumference size using the string (wrap the string around the width of the egg and then
measure it on the ruler) and record final circumference for group data in data table 2.
_____14. Find the DRY mass of the egg in grams using a balance and record final mass for group data in data table 3.
_____15. Wipe down your lab area, materials and put away all lab equipment. (throw away your spoon, cup, paper
towel)
_____18. Calculate the percent change in mass and circumference for each egg using the following equation (use the
same equation for circumference; just substitute ‘mass’ for ‘circumference’:
[(Final mass – Initial mass) / (Initial mass)] x 100%. = % change in mass
HINT: This value will be either a positive number, showing a gain in mass, or a negative number, showing a loss in
mass.
_____**19. Put your data on the board so that the others can copy your data. Copy the other groups’ data.
_____20. Construct a graph of percent change in circumference versus concentration of solute (corn syrup) from the
class data on the board. Be sure to provide a title and include labels and units for each axis of the graph. (T.A.I.L.S)
_____21. Draw a BEST-FIT line for all data points.
_____22. Answer the all the questions and follow directions for the formal lab report on the Egg Osmosis Lab.
**After calculating the data for your group, place your data on the board in the appropriate area. When all groups
have recorded their data on the board, complete this data table. Using the information in Data Table 4, create a
graph of the concentration of solute versus the percent change in circumference. Using the information in Data
Table 5, create a graph of the concentration of solute versus the percent change in mass. Be sure to provide a title
and include labels and units for each axis of the graph.
Data Tables:
Data table 1: Qualitative Data of the Chicken Egg (cell)
MY GROUP’S SOLUTION _________________________________________________________________
Appearance
Before (Day 2)
After (Day 3)
DI
25%
50%
Fructose
Fructose
Color
75%
Fructose
100%
Fructose
Shape
Data table 2 (QUANTITATIVE): Effect of Solution on Egg’s Circumference (GROUP DATA)
MY GROUP’S SOLUTION _________________________________________________________________
Initial Circumference
Final Circumference (g)
% Change in
(cm)
Circumference
Data table 3 (QUANTITATIVE): Effect of Solution on Egg’s Mass (GROUP DATA)
MY GROUP’S SOLUTION _________________________________________________________________
Initial Mass (g)
Final Mass (g)
% Change in Mass
Data table 4 (QUANTITATIVE): Effect of Solution on Egg’s Circumference (CLASS DATA)
% Change in
% Change in
Circumference (Group
Circumference
#1)
(Group #2)
Egg 1 (DI water)
Egg 2 (25% Fructose and 75%
Water)
Egg 3 (50% Fructose and 50%
Water)
Egg 4 (75% Fructose and 25%
Water)
Egg 5 (100% Fructose)
Data table 5 (QUANTITATIVE): Effect of Solution on Egg’s Mass (CLASS DATA)
% Change in Mass (Group % Change in Mass (Group
#1)
#2)
Egg 1 (DI water)
Average (% Change
in Circumference)
Average (% Change
in Mass)
Egg 2 (25% Fructose and 75%
Water)
Egg 3 (50% Fructose and 50%
Water)
Egg 4 (75% Fructose and 25%
Water)
Egg 5 (100% Fructose)
Results/Data Analysis:
1. Graph #1: Create a line graph, which shows the relationship between the concentration of the solute and the % change in
circumference.
a. REMEMBER T.A.I.L.S (USE THE WHOLE GRAPH-you may need to use decimal intervals)
2.
Graph #2: Create a line graph, which shows the relationship between the concentration of the solute and the % change in
mass.
a. REMEMBER T.A.I.L.S (USE THE WHOLE GRAPH)
3. Use the arrows to show the movement of water for each egg.
4. Identify the solutions tested as hypertonic, isotonic, or hypotonic relative to the egg.
5. Describe below what happened to each egg (stayed the same, swelled, shrunk).
Distilled Water
25% Fructose
50% Fructose
______________________
_________________________
__________________________
________________________
__________________________
___________________________
75% Fructose
100% Fructose
Vinegar
__________________
_____________________
___________________
__________________
______________________
___________________
Conclusion/Post-lab Questions-Answer the following questions:
1. What was the percentage of corn syrup in your group’s solution?
2. Was your corn syrup solution a hypotonic, hypertonic, or isotonic solution on the egg?
3. Explain your corn syrup solution’s effect on the egg.
4. What is an isotonic solution?
5. What effect would an isotonic solution have on the egg? Explain.
6. What is the approximate percentage of corn syrup that would make an isotonic solution for the egg (look at your
data and graph)?
7. Explain how your group would design an experiment to test question 6 above.
8. Define diffusion and osmosis, and explain the difference between them.
9. A cell has an internal salt concentration of 12 ppt (parts per thousand), and its external environment has a concentration of
35 ppt. Draw a picture of this cell and use arrows to indicate the direction water will flow. What will happen to this cell?
10. Sharks store urea (equivalent of urine in humans) in their body tissues. Why might a shark do this? (Hint: think of urea as
a salt/solute) (Hint: Sharks live in oceans (saltwater))?
11. What type of beverages would best re-hydrate your cells? Why?
12. What types of drinks should be avoided? Why?
13. Why are fresh vegetables sprayed with water at the supermarket?
14. Roads are sometimes salted to melt ice. What does this salting do to the plants along roadsides and why?
15. If you were stranded on a desert island, why is it worse to drink the ocean water than no water at all?,
16. Why does salt water make a good weed killer?
17. Why is sugar used to preserve fruit?
18. In 3-5 meaningful sentences describe what you have learned about cell transport. Be sure to include important vocabulary
to explain yourself.
Using your graph, answer the following questions.
19. What is the percent corn syrup with a 50% change in mass?
20. What is the percent corn syrup with a 25% change in mass?
21. What is the change in mass in 75% corn syrup?
22. What is the change in mass in 100% corn syrup?
23. What is the change in mass in 0% corn syrup?
24. If the cells in your large intestine (colon) were exposed to a hypertonic solution,what would happen? Explain.
25. If the cells in your large intestine (colon) were exposed to a hypotonic solution, what would happen? Explain.
26. AGAIN, Look closely at your graph: Make a hypothetical isotonic point for at what concentration of corn syrup will
make an isotonic environment for your egg (cell). CIRCLE that point on your MASS graph.