27 Jun bio-Experiment 1: Tonicity and the Animal Cell
Question
Experiment 1: Tonicity and the Animal Cell
In this experiment you will explore the effects of osmosis on eggs. An egg is
surrounded by a permeable membrane and a hard shell. To observe the effects
of osmosis the shell will first need to be removed.
Materials
Acetic Acid (Vinegar)
4 Pieces of Aluminum Foil (to
cover beakers)
(4) 100 mL Beakers
*Distilled water
*4 Eggs
10 mL Graduated Cylinder
100 mL Graduated Cylinder
100% Sugar Solution (Corn Syrup)
Stirring Rod
*You Must Provide
Note: This lab requires at least one day to prep and at least one day for
observations. For best results, please use a medium or large sized egg. Jumbo
or extra large eggs are too large for the experimental set-up.
Procedure:
1. Set out four beakers with one egg in each beaker.
Note: Always wear gloves when handling raw eggs.
2. Cover each egg with acetic acid (vinegar).
3. Cover each beaker with a piece of foil and allow the eggs to sit for 24
hours. Keep foil for entire experiment. You will need it later in the
experiment.
4. You will be placing eggs (cells) in different
tonicities and observing the results. Develop
a hypothesis and record it in the data section
for this experiment.
5. After 24 hours, check to see if the egg shell
is dissolved by gently taking out each egg
and rinsing with a small amount of water.
The eggs should have a yellow tint to them
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Figure 2: An egg that h as
been soaked in vinegar and
rinsed with water. Some white
shell remains.
and you should be able to lightly squish the egg between your fingers
(Figure 2). BE CAREFUL TO NOT BREAK THE EGG.
6. If any of the eggs still have a hard shell after 24 hours allow the eggs to sit
for another 12 – 24 hours.
7. Once the egg shells have been dissolved remove them from the vinegar.
HANDLE EGGS CAREFULLY. THEY CAN EASILY BREAK.
8. Rinse out and dry all four beakers.
9. Label one beaker 100 % distilled water, one 100% corn syrup solution,
one 10% corn syrup/90% water solution and one control.
10. In the beaker labeled 10% corn syrup/90% water solution, prepare a
10% sugar solution by mixing 45 mL of distilled water with 5 mL of corn
syrup. Mix well with a stirring rod. Record the initial volume in Table 1.
11. In the beaker labeled distilled water, measure and pour 50 mL of distilled
water. Record the volume in Table 1. The egg should be covered. Add or
reduce the amount of water if necessary. Record the initial volume in Table
1.
12. In the beaker labeled 100% corn syrup solution, measure and pour 50
mL of corn syrup (100% sugar solution). The egg should be covered. Add
more corn syrup if necessary. Record the initial volume of the solution in
Table 1.
13. In the beaker labeled control, do not add any solution. Record the
volume in Table 1.
14. Add one egg to each beaker and cover with foil.
15. Let the eggs sit for 24 hours. In the meantime, develop a hypothesis
stating how you believe each egg will be affected by the solution in the
beaker over the 24 hour period. Record your hypothesis in the Post-Lab
Questions section.
16. After 24 hours have passed, observe the eggs. If you do not see any
noticeable difference let the eggs sit for another 12 – 24 hours.
17. After the eggs have rested for 24-48 hours in the solutions carefully
remove them from the beakers. Make sure to note which eggs came from
each beaker. Be careful to not spill the solutions.
18. Record the final volume of each solution using a graduated cylinder and
record your results in Table 1.
19. Observe the eggs. Draw your observations in the in Table 2 of data
section.
Data
Hypothesis:
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LLC.
All Rights Reserved
Table 1: Osmosis Results
Volume (mL) Before
Osmosis
Solution Type
Volume (mL) After
Osmosis
100% distilled water
100% corn syrup
10% corn syrup/ 90% distilled water
control
Table 2: Observations of Eggs After Osmosis
100% Distilled Water
100% Corn
Syrup
10% Corn syrup/ 90%
Distilled Water
Control
Post-Lab Questions
1. Record your hypothesis from Step 15 here. Be sure to include scientific
reasoning to support your predictions.
2. How do each of the three eggs placed in solution compare to the control
egg?
3. For each beaker, identify whether the solution inside was hypotonic,
hypertonic, or isotonic in comparison to the control beaker.
4. What was the direction of osmosis in the beaker labeled 100% distilled
water? Did the egg in this beaker burst?
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LLC.
All Rights Reserved
5. Was there a volume in the control beaker after 24-48 hours? If so, why
do you think this is? If not, why do you think this is?
6. Which solution contained a dehydrated cell? Think about someone having
a high sugar diet. Hypothesize how their cells might be affected by
osmosis?
7. Osmosis is how excess salts that accumulate in cells are transferred to
the blood stream so they can be removed from the body. Explain how this
process works in terms of tonicity.
2013 eScience Labs,
LLC.
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