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) / Mean % Change in Mass
0.1
0.2
0.3
0.4
0.5

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..