VCE BIOLOGY: Unit 1: Investigating osmosis in chicken eggs
In this procedure, you can observe osmosis in an animal system by using chickens’ eggs from
which the shells have been removed by dissolving in acetic acid (vinegar). Osmosis is the
movement of water through a semi-permeable membrane. The eggs are weighed and placed in
solutions of different strength for 1 hour before being weighed again. The egg is not a single
animal cell. However the egg’s membrane is selectively (partially) permeable, so it is a good
model to show osmotic effects in animal tissue.
Aim: To observe the effect of osmosis on chicken’s eggs placed in different concentrations of
saline solution.
Materials and Equipment:
Balance
De-shelled eggs
Sodium chloride solutions in a range of concentrations, 0% (distilled water); 1% saline, 2% saline,
5% saline and 10 % saline.
(150 cm3 of each salt solution to be used.)
Paper towel
Beaker, 200 cm3
Method:
1. De-shell the eggs in acid overnight.
2. Ensure the egg is dry by gently patting it with a paper towel.
3. Place the egg on a balance and record the mass in a suitable table.
4. Put the egg in a 200 cm3 beaker.
5. Pour in enough sodium chloride solution to cover the egg. Record the concentration of
sodium chloride used.
6. Leave the egg until next lesson.
7. Pour the sodium chloride solution off the egg.
8. Dry the egg carefully using a paper towel.
9. Place the egg on the balance and record the mass in the table.
10. Calculate change in mass and percentage change in mass.
11. Compare the results for the different concentrations of sodium chloride.
Results:
Draw a table to collect your results – showing the % change in mass on a bar graph.
Discussion:
1. (a) What is a hypotonic solution?
(b) Would water move into or out of the egg in a hypotonic solution?
(c) Which solutions are hypotonic and how do you know?
2. (a) What is a hypertonic solution?
(b) Would water move into or out of the cell?
(c) Which solutions are hypertonic?
3. (a) What is an isotonic solution?
(b) Where any of the solutions isotonic and how do you know?
Remember to write a conclusion explaining any unexpected results.
From: http://www.practicalbiology.org/areas/intermediate/exchange-ofmaterials/osmosis/investigating-osmosis-in-chickens-eggs,46,EXP.html
Sourced 3/2/2010.