The Effect of Sugar Solution on Plant Cells

2. Take 18 potato chips out of their 0.3M solution using tweezers and put then onto a ceramic cutting tile. Using a ruler and scalpel measure and cut the chips to 50mm. Be careful not to cut yourself with the scalpel by pointing it away from you when using it.

3. Using the tweezers place 3 potato chips into each petri dish. There are 3 chips in each dish because this makes it a fairer test. Start the stopwatch.

4. After 45 minutes take the potato chips out of the solutions and measure them again using the ruler. Record measurements.

Variables - The variables in this experiment are the strengths of the sugar solutions, the size of the potato chips, the amount of solution in the petri dishes and the amount of time that the potato chips are left in the solution.

Preliminary Investigations - We did a preliminary investigation where we put onion cells onto slides and looked at the cytoplasm under a microscope, then saw how sugar solution made the vacuoles shrink away from the cell walls. We also did an experiment the same as this one to see how sugar solution affects plant cells.

Results -

Strength of solution (M)

Starting length of chip (mm)

Finishing length (mm)

Finishing length (mm)

2

Finishing length (mm)

3

Average change in length (mm)

.0

50

48

47

49

-2

0.8

50

48

49

49

-1.33

0.6

50

49

49

48

-1.33

0.4

50

49

49

49

-1

0.2

50

50

49

50

-0.33

Distilled water

50

50

52

51

+1

Analysis - I have found out that if you put potato chips in a sugar solution with a higher concentration than they have been stored in, they shrink and if they are put in a lower concentration solution or distilled water, they expand.

Graph -

Trends and Patterns - My graph has a line of best fit that is a smooth curve. Most of the results fit well into the smooth curve, the exceptions being the two anomalous results, for 0.6M and 0.8M. The change in the length of the potato chips ranges from shrinking 2mm to growing 1mm, which is proportional considering the chips were stored in 0.3M sugar solution.

Conclusion - Most of the results turned out as they are expected, the chips in solutions with a concentration higher than 0.3M shrunk, and the chips that were in the distilled water got bigger. The reason my results turned out like this is osmosis. In the petri dishes where the concentration of the solution was higher than 0.3M the water from inside the cells of the potato chips moved into the solution, because there was a lower concentration of water there than inside the cells. In the dishes where the concentration of the solution was lower than 0.3M the water moved from the solution into the cells of the potato chips because there was a lower concentration of water inside the cells than in the solution.

My results support my prediction because osmosis affected the length of the potato chips in the ways that I predicted. The results for the sugar solutions of 1.0M, 0.8M, 0.6M and 0.4M are how I predicted they would be, the potato chips shrank because of osmosis. The results for the distilled water also corresponded with my prediction. The potato chips that were in the distilled water grew, although my prediction for the 0.2M solution was wrong, I predicted that they would grow, but they shrunk. The reasons for this could be explained in the evaluation.

Evaluation - The procedure used was not as accurate as it could have been, but the results obtained were relatively good. Some of the results, such as the result for the 0.2M solution were not accurate, the chips should have grown according to osmosis, but they shrunk. This could be due to bad measuring on my behalf.

There were two anomalous results, one that was very anomalous and one that was only slightly anomalous. The 0.6M solution was slightly anomalous, but not so much that it really stood out from the line of best fit. The 0.8M solution was very anomalous. This could have been because the chips were not measured and cut very well.

The procedure was quite suitable because it was relatively simple to do and the results were easy to obtain and were quite accurate. The experiment would be improved if there was more time available because the longer the chips are in the solution, the better the range on the change in length would be. The chips could also have been measured and cut more accurately, as they were done in a bit of a hurry and some of the chips might not have been 50mm exactly.

The results were quite reliable, although the anomalous result (0.8M) was quite a long way off the line of best fit. I think that the evidence is accurate enough to support my conclusion and to say that my prediction was right. Most of the results do fit in with the trend they are expected to follow and the line of the best fit is a good smooth curve.

To make the evidence more reliable there are a few improvements that could be made to the experiment and also further work that could be done. The experiment could be done more accurately, the potato chips could be measured better and also they could be left in the solution longer to obtain better results. Further work could be to weigh the potato chips instead of measuring them, as this could be more accurate and support my conclusion and prediction better. The enquiry could also be extended by doing the experiment with different concentrations of sugar solutions to the ones that were used in this experiment.

Hannah Prince 11G