Name _______________________________________________
Date __________________________________________________ Period ___________
Osmosis Egg Lab
Introduction:
This lab activity will use a chicken egg as a model for a human cell. We will learn about osmosis by exposing the
chicken eggs to hypertonic and hypotonic environments. We will have 5 different concentrations of fructose solution
0% fructose, 25% fructose, 50% fructose, 75% fructose, and 100% fructose.
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.
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).
Pre-lab and Hypotheses:
Distilled Water
25% Corn Syrup
50% Corn Syrup
75% Corn Syrup
(Pure Water)
75% Water
50% Water
25% Water
100% Corn
Syrup
Will the solution be
Isotonic, Hypotonic, or
Hypertonic to the egg?
Will the egg shrink or swell?
Water move in? Water
move out? Water move in
and out?
1.
Experiment Design: What is the Control, Experimental Group, Independent variable, Dependent variable(s),
and 3 Controlled variables?
a.
Control Group:
b.
Experimental Group:
c.
Independent Variable:
d.
Dependent Variable:
e.
Controlled Variables (3):
2.
Why is an egg being used for this experiment?
3.
Explain why vinegar was used first.
4.
What is the difference between diffusion and osmosis?
1
Materials:
 one raw egg
vinegar (approximately 5%
acetic acid)
plastic cups
beakers
paper towels (or tissues)
digital balance scale
corn syrup
distilled water (tap water will
work)
graduated cylinder
string
pen
ruler
stirring rod
masking tape (label the cups)
weigh boat
Procedures
Day 1
Warning! The eggs are raw. If they are mishandled, especially after the shell has been dissolved, it could be
messy. Salmonella, a bacterium commonly found in poultry and eggs, causes food poisoning. To minimize
the risk of Salmonella, make sure the students wash their hands with antibacterial soap once they have
completed each day’s activities.
1. Get out 1 raw chicken egg from your instructor.
2. Place each egg in an individual container that is provided.
3. Add enough distilled white vinegar to each container to cover the egg. (Note that the egg will probably float)
4. Let the egg soak for 2 minutes and observe what happens
5. Record Observation on your Qualitative Data Table.
6. Label your containers with your lab group and class period.
Day 2
1. Observe and record any changes in your egg on your Qualitative Data Table.
2. Carefully lift the eggs out of container and carefully rub any shell remnants off with your fingers.
3. GENTLY Pat the eggs dry… carefully with a weigh boat, measure the mass of your egg. Record it on your
quantitative data table.
4. Use string to measure the widest circumference (not the oblong circumference) of the egg. Record it on your
quantitative data table.
5. Describe the appearance (color) and shape of the assigned egg in data table 1 (Day two).
6. Rinse out the container.
7. Make your assigned concentration of fructose solution.
For instance, the 0% group will pour 500 mL distilled water into their beaker. The 25% group will pour 125 ml of
corn syrup and 375 mL of tap water into their beaker. The 50% group will pour 250 ml of corn syrup and 250 mL of
tap water into their beaker. The 75% group will pour 375 ml of corn syrup and 125 mL of tap water into their
beaker. The 100% group will pour 500 ml of corn syrup into their beaker.
8.
9.
10.
11.
1.
2.
3.
4.
5.
6.
Pour your assigned concentration of fructose solution (corn syrup) in the container.
Gently put your egg in the solution (it may float).
Add the concentration to of your solution to the label on your container.
Place containers where assigned.
Day 3
Remove your egg from fructose solution and gently blot dry on a paper towel.
After the eggs have been in their respective solutions for two days, they will be sticky, especially the higher corn
syrup concentrations (75% and 100%). Therefore, great care must be given when drying off the outside of the egg.
The 100% group will have the biggest challenge. But with patience, perseverance, and plenty of dry, soft paper
towels, they can get the outside of the egg dry.
Describe the appearance (color) and shape of the assigned egg in data table 1 (Day three).
Measure the mass and circumference of your egg again. Record them on your quantitative data table.
Rinse out container and throw it away. The eggs are a salmonella risk and need to be disposed of properly. Wipe
down lab area, put away all lab materials. (throw away spoon, cup, paper towel)
Calculate percent change in mass and circumference as shown below: Same equation for circumference; just
substitute ‘mass’ for ‘circumference’:
%change in mass = mass after - mass before
mass before * 100
HINT: This value will be either a positive number, showing a gain in mass, or a negative number, showing a loss in
mass.
2
Data Tables
Data Table 1: Qualitative Data of Chicken Egg (cell) (GROUP DATA)
Observations
Day One
Day Two
Day Three
Quantitative Data
Data Table 2: Effect of Solution on Egg’s Circumference and Egg’s Mass (GROUP DATA)
Mass (grams)
% change
Circumference
(cm)
%
change
Day One (before vinegar treatment)
Day Two (after vinegar treatment)
Day Three (after corn syrup treatment)
My Group’s Solution:
Data Table 3: Effect on solution on Egg’s Circumference and Egg’s Mass (CLASS DATA)
Concentration
of Fructose
AVG % Change Mass
AVG % Change Circumference
0
25
50
75
100
Graphs:
As part of your formal group lab report, you will create a two lines graphs in excel which show % change in mass
over the different concentrations and the other needs to show the % change in circumference over the different
concentrations.
Remember the independent variable is on the x-axis and the dependent variable on the y-axis. (HINT: you will have
some points that should go in the negative direction!)
YOU WILL DRAW A BEST-FIT line for all data points.
You need to have a:
Title
Axes (correct)
Interval (consistent)
Labels and Units
Scale and Size
3
Analysis:
1. Use arrows to show the movement of water for each egg.
2. Identify the solutions tested as hypertonic, isotonic or hypotonic relative to the egg.
3. Describe below what happened to each egg (stayed the same, swelled, shrunk).
Analysis Questions:
1. Was your corn syrup solution a hypotonic, hypertonic, or isotonic solution on the egg? Explain your corn syrup
solution’s effect on the egg.
2.
What is an isotonic solution? What effect would an isotonic solution have on the egg? Explain.
3.
What is the approximate percentage of corn syrup that would make an isotonic solution for the egg (look at
your graph)?
4.
After exercise, what type of beverages do you think would best re-hydrate your cells? Why? What types of
drinks should be avoided? Why?
5.
Why are fresh vegetables sprayed with water at the supermarket?
6.
Roads are sometimes salted to melt ice. What does this salting do to the plants along roadsides and why?
7.
In 3-5 meaningful sentences describe what you have learned about cell transport. Be sure to include important
vocabulary in your explanation.
4