Observing Osmosis Lab
Chapter 15; section 2
Name ________________
Period_______________
It is difficult to see osmosis occurring in cells because most cells
are so small. However, a few cells can be seen without the aid of a
microscope. This activity will show you how osmosis affects an
egg cell.
Goals:
Observe osmosis in an egg cell.
Determine what affects osmosis.
Materials: egg
Clear jar
Vinegar (250 ml)
Corn syrup (250 ml)
String and ruler for measurement
Graduated cylinder
Small bowl
Spoon
Procedure:
Day 1
1) Add exactly 250 ml of vinegar to the jar.
2) Record this amount in the data table.
3) Use string and a ruler to measure the long
circumference and the short circumference of the egg.
4) Record these measurements in the data table.
5) Carefully lower the egg into the jar (use the spoon).
6) Cover the jar to prevent evaporation.
7) Label your jar and store in a safe place.
8) Observe the egg in the vinegar. Write down anything that you notice and record in the observation
table.
Data Tables:
Long Circm.
Short Circm.
Vinegar Amount
Egg
(day 1)
Egg
(day 3)
Egg
(day 4)
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Observations
Day 1
(egg in vinegar)
Day 3
(egg in bowl)
Day 4
(egg in bowl)
(corn syrup in jar)
Carefully handle your eggs today; you do not get another one!
Day 3
1) Take the egg out of the jar and place in bowl.
2) Observe the egg and record in the observation table.
3) Find the long and short circumference of the egg in
the bowl.
4) Record the measurements in the data table.
5) Measure the amount of vinegar left in the jar.
6) Record this amount in the data table.
7) After you have cleaned the jar, place the egg back
into the jar.
8) Pour enough corn syrup into the jar to cover the egg.
9) Cover the jar and store in a safe place.
Day 4
1) Remove the egg from the jar.
2) Rinse off any excess corn syrup and place in the
bowl.
3) Measure the long and short circumference of the egg.
4) Record the measurements in the data table.
5) Make any other observations about the egg and the
corn syrup and list in your data table.
6) Clean up your lab station.
* check out the special disposal directions on the board.
Questions:
1. Use your textbook or notes to find the definition of osmosis.
2. Explain what happened to the egg shell. What observations
do you have to support your explanation?
3. What happened to the size of the egg after sitting in the
vinegar for two days?
4. What could explain this change in size after the egg has been
in the vinegar?
Equation for vinegar and egg shell:
Hypothesis: What will the egg look like on Day 4?
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5. Explain the change in the egg after it was in the corn syrup
for 24 hours.
6. Use your observation of the corn syrup to help explain what
happened to the egg.
7. Draw a cell representing the environments; show the
direction of diffusion of water into or out of the egg cell.
Make sure to label all parts important to this lab in your
diagram!!
Teacher Page: (for class of 140)
Materials: 3 dozen eggs
3 large bottles of vinegar
9 bottles of corn syrup
plastic wrap
string/ruler for measuring circumference
Jar
Spoon
Bowl
How do materials get into and out of cells?
Save one egg from the end of the day and place it into a jar with
pure water.
Discussion:
Draw 2 containers on the board that contains cells.
Show the concentrations inside and outside of the
egg with percentages.
Have the students discuss their observations and
infer how diffusion occurred in each egg.
Further questions about putting the egg back into
the vinegar. Show the egg that was placed
into the water and left overnight.