Osmosis in Carrots.
The aim of this experiment is to demonstrate the effect
of osmosis on carrot tissue by placing them in different
concentrations of salt solution, preferably over night.
Apparatus:
5 boiling tubes
Salt solutions 0.1, 0.2, 0.3, 0.4 and 0.5 M
5 cylinders of tissue cut from the same carrot using a cork borer
Accurate balance
Marker pens
Boiling tube rack
Diagram:
Method:
1. Cut the carrot pieces to the same diameter (using the cork
borer) and then cut them to the same length (20mm), using a
ruler to measure them.
2. Blot the carrot cylinders dry using a paper towel. This is done to
remove any excess liquid from the damaged cells, so it doesn’t
affect the initial mass readings.
3. Weigh each carrot cylinder, note its mass in your results table,
then place it in the boiling tube so that it is covered in solution.
4. Repeat 3 times (i.e. set up 3 test tubes) for each concentration of
solution.
5. Leave for at least one hour and preferably over night.
6. Remove the cylinders from the solution, blot them dry and re-weigh
them. Note the final mass of the potato cylinders in your results
table.
7. Calculate the Change in mass, then the percentage change in mass.
8. Your teacher may ask you to calculate the class average weight
change or draw a graph showing your data.
Group Results:
Concentration
of Sucrose
Solution
(M)
Initial
Mass
(g)
Final
Mass
(g)
Change in
Mass
(g)
% Change
in Mass
Mean %
Change in
Mass
Class results:
Concentration of Sucrose
Solution (M)
0.1
0.2
0.3
0.4
0.5
Mean % Change in Mass
9.
Draw a graph of the class results and use it to estimate the
concentration of cell sap in the carrot tissue. This will be the
concentration of solution that is isotonic to the plant cells i.e.
where no net gain or loss of water occurs.
10.
Write a conclusion and evaluation for your scientific report..