cell
I also predict that if you double the concentration of the sucrose the rate in it shrinking will also double.
This is a graph in which I can make a prediction. At point A osmosis is taking place but the concentration is the same inside as it is outside.
At point B (High water concentration) there is no sign that the cell has increased in size so this suggests that the cell is fully turgid.
At point C (low water concentration) there is no sign that the cell is shrinking further in size so this suggests that the cell is fully plasmolysed.
Method
Apparatus
1 molar sugar solution, distilled water, potato, mass balance, 5 test tubes, scissors, labels, measuring cylinder, cling film and a test tube holder.
Preliminary
For the preliminary work we suggested that the concentrations were the best and that they were more accurate than any smaller amount of concentrated liquid and too much was not really need because there was not much difference. There is another thing that we will have to be careful about which is that when we are taking out the potatoes that we do not spill some of the liquid.
This is a table of how the concentrations were mixed
Volume of distilled Volume of 1molar Concentration of sugar
10 0 0.0
8 2 0.2
6 4 0.4
4 6 0.6
2 8 0.8
0 10 1.0
Step-by-step
- Collect the equipment listed. And arrange them as seen in the diagram.
- Cut the potato so all weigh roughly the same weight. To get the right concentration use the measurements from above.
- Now place all of the potato chips into the tubes with the liquid solutions and cover the top with cling film.
- Come back 24 hours later and record the results and do this on four consecutive days.
Results
Graph
See Graph paper.
Conclusion
The evidence obtained from this investigation supports the prediction I made. It shows that the potato cells increase mass in solutions with a high water concentration and decrease in mass in solutions with a low water concentration. At concentrations above 0.6m, there appears to be no further weight loss so this is suggesting that the cell is fully plasmolysed. Then the cells start drawing in a very little amount of water that increases the weight slightly.
Evaluation
The graph obtained in the results has a great connection to the one in the prediction. This predicts that the experiment was fairly accurate.
Although the accuracy was fairly good there were a few things that could be improved. The concentrations were measured in a measuring cylinder and could be more accurate using a titration. Also when the potato was dried to remove surface liquid it was not necessarily done the same with each potato, a more accurate and uniform way of drying would improve the accuracy further.
