In this demonstration, the water moves in both directions through the membrane; the flow is greater from the vessel of pure water, however, because the concentration of water is greater there, that is, fewer dissolved substances exist in this solution than in the sugar solution. The level of liquid in the tube of sugar solution will eventually rise until the flow of water from the tube of sugar solution, under the influence of hydrostatic pressure, equals the flow of water into the tube. The hydrostatic pressure establishing this equality of flow is called osmotic pressure. A variety of physical and chemical principles are involved in the osmosis in animals and plants. Osmosis affects the size and turgidity of a plant cell, this means that when a plant cell is placed in a solution that has a higher sucrose concentration the plant cell, by using osmosis will expand and therefore becomes turgid, Turgid means swollen and hard
The diagram below explains this process.
Preliminary work
Method
The apparatus was set u as shown below:
We measured the length of the potato slices before entering and on exiting the sucrose solution after 20 minutes.
Results
Conclusion
I have concluded that in my investigation I need to be extremely accurate while taking my results. I also need to repeat my experiments at least 3 times and take the average. This will give me a more accurate result and therefore a more successful experiment. I do need to be accurate with the time in which I take my results by starting the separate slices off at intervals of 30 seconds, this will give me enough time to take the readings and move on to the next one without exceeding the time limit.
Hypothesis
I predict that my main investigation will go something like the first one, where the highest concentration of sucrose will make the plant cells shrink, and therefore the solution with the lowest concentration will force the plant cell to expand. I also believe there will be some correlation between sucrose concentration and the expansion of the cell.
Prediction
I predict that the higher the concentration of sucrose, the more the cell will expand.
Method
I will place 4 pieces of potato in 4 separate beakers containing different concentrations of Sucrose. I will keep the potatoes the same size so as to keep the experiment fair. I will repeat the experiment twice as to get a better set of results.
Apparatus
For my investigation I will need:
4 beakers
4 slices of potato
4 solutions with varying concentrations of sucrose
I will set up this apparatus as shown below.
