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An experiment to test the effect of concentration of sugar solution on potato cells

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An experiment to test the effect of concentration of sugar solution on potato cells by Claire Jaeger 11k September 2002 Background information: Osmosis is the passage of solvent molecules from a dilute solution into a more concentrated solution, through a semi-permeable membrane. Osmosis continues across a membrane until the two solutions either side have reached the same concentration. We call this state equilibrium. Osmosis can be seen in living cells. The cell membrane in cells is semi- permeable and the vacuole contains a sugar solution. So when a cell is placed in distilled water, a high water concentration, water will move across the semi-permeable membrane into the cell, a lower water concentration, by osmosis. The cells swells until there is no space left. The cells increase in length, volume and mass because of the extra water but do not burst because of the cell wall. This cell is now referred to as turgid and the cell can not take on any more water even though the solutions have not reached equilibrium. In reverse, when cells are placed in a concentrated solution of sugar the cells lose water across the membrane and shrivel. This is referred to as flaccid. Plan: Aim: To investigate what effect different concentrations of sugar solutions have on potato cells. Fair Testing: In this experiment on osmosis I would like to control all the variables and keep them constant but I will change the concentration of the sugar solution. ...read more.


Do the same for 0.1 - 0.6 moles of sugar solution. 6. Take 7 of the potato cylinders and mark them with an X. 7. Take another 7 and colour the base in. 8. Take the last 7 an put a large dot on them. 9. Record the mass of each of the cylinders and record in a table. 10. Place one of each of the differently marked cylinders in each of the beakers and record which order they went in. 11. An hour later take the first cylinder you put in and take some blotting paper and remove as much of the surface liquid as possible. 12. Put the cylinder on the scales in the weighing boat and record the measurement. 13. Return the cylinder to its beaker 14. Do points 11 to 13 for all the other cylinders. 15. Then another hour later do points 11 - 14 again. Results: Original mass (g) 2nd mass (g) 3rd mass (g) Distilled water 1.983 2.27 2.36 Distilled water 1.95 2.18 2.27 Distilled water 1.94 2.11 2.3 average 1.96 2.19 2.31 0.1 mole 1.98 2.23 2.39 0.1 mole 1.95 2.14 2.32 0.1 mole 1.81 2.05 2.1 average 1.91 2.14 2.27 0.2 mole 1.69 1.86 1.86 0.2 mole 1.91 2.08 2.06 0.2 mole 1.91 2.84 2.32 average 1.84 2.01 2.08 0.3 mole 1.86 2.05 1.96 0.3 mole 1.85 2.08 1.97 0.3 mole 1.89 2.09 1.98 average 1.87 2.07 1.97 0.4 mole 1.84 1.73 1.86 0.4 mole 1.85 1.95 1.78 0.4 mole 1.91 1.95 1.74 average 1.87 1.88 1.79 0.5 mole 1.82 1.57 1.74 ...read more.


Stirring may help as it would stop a concentration around the sample Further work could be carried out to include concentrations that increased in 0.05 M rather than 0.1. This would increase the accuracy and improve the graph. Other investigations could include using different varieties of potato or different plant tissues e.g. carrot, apple. I could also extend this experiment by repeated exactly as before. However this time I could take more results at the mole levels 0.20, 0.21, 0.22,0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30. This would produce much more accurate results. Other variables in the experiment could be changed for example instead of changing the mass of the potato the species of the potato could be changed. For example I could use a new potato and a really old potato. Also the shape and size could be changed. However this would not affect the results much. This is because the variable would only change the rate of osmosis because of a different weight and size. Temperature could also be changed for example the samples could be placed in different water baths and brought up to different temperatures to see if temperature played its part in the osmosis of potatoes. 5 sets of 5 potatoes could be placed in water baths at 10 C, 20 C, 30 C, 40 C, 50 C and 60 C. I could also as I mentioned earlier, investigate into the results I got for 0.3 and 0.4 moles. ...read more.

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