Cells in action: an egg-speriment
Name:
Team:
Period:
Pre-lab
1. An egg is sitting in a carton in your refrigerator. What is the internal environment of the egg like?
How is this different than the external environment?
2. We removed the shell from the egg so only a thin membrane remains. What do you think will happen
if we change the external environment of the egg? What do you think will happen if we put the egg in
pure water?
What do you think will happen if we put the egg in water with a lot of sugar in it?
3. In question 2, you made a prediction about what would happen to the egg. How will the internal
environment of the egg change if your prediction is true about the pure water?
How will the internal environment of the egg change if your prediction is true about the water with a
lot of sugar in it?
4. What is a control?
What will be your control for the egg lab?
Procedure
Materials:
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3 eggs soaked in vinegar
String for measuring circumference
Sugar solution
Distilled water
3 cups
Day 1
1. Carefully rinse off your three eggs, rubbing them gently under warm water to remove all of the white
egg shell. When you are done, your egg should be a slightly opaque yellowish color with minimal white
spots.
2. Put a piece of masking tape on your cup to serve as a label. Label cup 1 “control”, cup 2 “50% sugar
water”, and cup 3 “pure water”. Also write your team name and period on your labels.
3. One of your eggs will be your control egg. Use the scale to record the mass of the egg and record it on
your Data table below. Wrap a string around the middle of your egg and record the length of the string
required to go all the way around as the circumference of the egg and record it in your Data table
below. Make a qualitative observation about your egg and record it on the Data table below. Place
this egg in your “control” cup.
4. Another one of your eggs will be your “50% sugar water egg”. Record the mass, circumference, and
qualitative observations as described in step 3 for this egg. Record your data in the “50% sugar water”
row on the table below. Place that egg in your “50% sugar water” cup.
5. Your last egg will be your “pure water”. Record the mass, circumference, and qualitative observations
as described in step 3 for this egg. Record your data in the “pure water” row on the table below. Place
that egg in your “pure water” cup.
6. Treat your control egg as you decided in the pre-lab above.
7. Pour enough 50% sugar water from the jug labeled “50% sugar water” over the “50% sugar water” egg
to cover it. Cover the cup with plastic wrap.
8. Pour enough pure water from the jug labeled “distilled water” over the “pure water” egg to cover it.
Cover the cup with plastic wrap.
9. WASH YOUR HANDS
Storyboard of Day 1 procedure. For each step of the procedure above, draw a picture of what it will look like,
and briefly summarize the procedure in the space provided below.
Step 1 (draw the procedure here)
(summarize the procedure here)
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Step 8
Step 9
Day 2
1. Remove the control egg from its control environment. Record the mass, circumference, and
qualitative observations of the “control egg” as you did in step 3 of the day 1 procedure. Record in
your data table.
2. Carefully rinse the sugar water off of the 50% sugar water egg using water gently coming out of the
faucet and blot the egg dry with a paper towel. Record the mass, circumference, and qualitative
observations of the “50% sugar water egg” as you did in step 3 of the day 1 procedure. Record in your
data table.
3. Carefully blot the “pure water” egg dry with a paper. Record the mass, circumference, and qualitative
observations of the “pure water egg” as you did in step 3 of the day 1 procedure. Record in your data
table.
4. Remove labels from your cups, wash and rinse them carefully, and clean up your lab station.
5. WASH YOUR HANDS.
Step 1
Step 2
Step 4
Step 5
Variables
What is your independent (manipulated) variable?
What is your dependent (responding) variable?
What are some variables that will remain the same (controlled variables?)
What will the environment of the control egg be like?
Step 3
Data
Mass on day 1
Mass on day 2
Percent change
Circumference on day 1
Circumference on day 2
Percent change
Control egg
Egg in sugar water
Egg in pure water
Control egg
Egg in sugar water
Egg in pure water
Observations on day 1
Control egg
Egg in sugar water
Egg in pure water
Graph your mass or circumference data here:
Observations on day 2
Analysis
1. What affect did the sugar water have on the internal environment of the egg? Use your data to
support your answer.
2. What affect did the pure water have on the internal environment of the egg? Use our data to support
your answer.
3. What affect did the control conditions have on the internal environment of the egg? Use your data to
support your answer.
4. There are several types of membranes: impermeable (nothing can pass through it), semi-permeable
(some things can pass through it), and permeable (everything can pass through it). Based on your
experiment, what kind of membrane does the egg have? Use your data to support your answer.
5. Draw what you think the cell membrane would look like here to allow for what you observed in this
lab.
6. Compare your data to the class data. Which do you think is “better” and why?