(P) How sugar solutions affect plant tissue

• 1. Cut up a potato into identical cylinders, and get some breakers with different sugar solutions in them. One should be pure water and the other should be a very concentrated sugar solution (e.g. 1 mol/dm^). Then you can have a few others with concentrations in between

  
• 2. You measure the massof the cylinders, then leave one cylinder in each beaker for 20 hours of so

  
• 3. Then you take them out, dry them with a paper towel and measure their masses again

  
• 4. If the sylinders have drawn in water by osmosis, they'll have increased in mass. If water has been drawn out, they'll have decreased in mass. You can calculate the percentage change in mass, and plot a graph

  
• By calculating the percentage change in mass, you can compare the effect of sugar concentration on cylinders that didn't have the same initial mass. An increase in mass will give a positive percentage change and a decrease will give a negative percentage change
• 5. The dependent variable is the potato mass and the indepenent variable is the concentration of the sugar solution. All other variables (volume of solution, tneperature, time...) must be kept constant in each case or the experiment won't be a fair test

  
• 6. Like any experiment, you need to be aware of how errors may arise. Sometimes they may occur when carrying out the method e.g. if some potato cylinders were not fully dried, the excess water would give a higher mass.

  
• You ca reduce the effect of errors by repeating the experiment and calculating a mean percentage change at each concentration
• You could also carry out this experiment using different salt solutions and see what effect they have on the potato mass