Osmosis in Potato cells

 

Henry Pearman

Results For Trial Run

Comments on the Trial Run

I think that my trial run went well because there were no really unordinary results in any of them. I was a bit surprised to see that the potato chips in the water didn’t increase in their size at all. The potato chips in the Diluted sugar were a bit strange because one of the increased in their size but the other one decreased in its size. The Concentrated solution went ok because there weren’t any major difference between the length after they had decrease pretty much the same apart from 1 mm in it but that was probably because one of them was slightly bigger than the other one.

Method for Main Experiment

        This is a list of the equipment I will need to use in the main experiment:

• 5 Small Beakers
• Measuring Cylinder
• Knife
• Tile

• Electronic Scales

• Ruler
• Water
• 1m solution
• 0.75m
• 0.5m
• 0.25

        

First of all get a reasonable size potato, which you think will give you enough chips, which will be the same size and then peal it using a knife and the tile. Cut the potato into a square shape so it is easier to cut the chips out accurately. Measure the chips accurately with a ruler so that they are all the same size then weigh then accurately, my chips measures out at 2.5g each make sure that all of your measurements are very accurate so that you make it as fairer test as

Henry Pearman

possible so your results are more accurate. Take 5 small beakers and the measuring cylinder; fill the measuring cylinder up with 80cm3 of each solution

and poor in over the potato chips in all 5 beakers. Label the beakers clearly with a pen so you don’t get them mixed up when you come to measure them. Place the beakers near a window so they can get natural light, we left our beakers there for 94 hours to see what would happen to them.

Safety in the experiment:

• When pealing the potato cut away from yourself.
• Keep fingers away from the knife.
• Wash hands after using the solutions.

Prediction.

        I think that the potato chips in the water will increase in size the most because the water is a dilute solution and the enzymes will travel through the potatoes semi-permeable membrane to a higher concentration, so the potato chip should increase in size. I also think that the longer I leave the potato chips in the solutions then the more they will increase in size. I predict that the more concentrated the solution then the more the potato chips will decrease in size because there will be more sugar molecules and they will not be able to pass through the semi-permeable membrane of the potato chips instead they will decrease in size because the water will leave the potato chips and go into the solution the chips is in.

Henry Pearman

Analysis and Conclusion

        The pattern I see is that the higher the concentration, the more the potato chips decrease in size and the lower the concentration the more the potato chips will increase in size. My graph quite clearly shows this because there is a slope in the line of best fit as it goes from water, which increased in size to 1m, which decreased in size. My prediction was right because I said the higher the concentration in the solution then the more the potato chips will decrease in size because the solution starts to move out of the chip because the solution outside it is a higher concentration. My prediction also said that the chips would increase in size the lower the sugar concentration in the solution and the chips did increase in size this is quite clear on my graph. There is only one result I think is a bit suspect and that is the 0.5m because I didn’t expect the chips to decrease in size that much because half of the solution still contained water molecules.

        My results have all formed this pattern because of Osmosis. The water has smaller molecules so they can pass through the potato chips semi-permeable membrane. The 0.25m solution has a few sugar molecules in it, but more water molecules so they will pass through the semi-permeable membrane into the potato so it will increase in size but not as much as the pure water solution because there are sugar molecules in the solution, the water passed into the potato because it was a higher concentration. The 0.5m solution has half of the solution sugar molecules and the other half water molecules so it decreased in size a lot because not enough water could pass through the semi-permeable membrane into the potato. I didn’t expect the 0.5m solution to decrease as much as it did because there were still a lot of water molecules in the solution so it shouldn’t decrease in size as much as it did. The 0.75m solution had more sugar molecules than water molecules so the water passed out of the potato chip into the solution because the solution was a higher concentration than the potato chip. The 1m solution was mostly sugar molecules so a lot of water passed out of the potato through the semi-permeable membrane to the solution because the solution was a higher concentration. In all of my solutions osmosis happened but in different ways because osmosis is when water moves from a lower concentration to a higher concentration.

        I have no doubts about my prediction because I predicted the same as my results so I am quite pleased with how the experiment went.

        

Evaluation

        I think that my results were quite accurate; they are as accurate as I could get them at the time. I could have made my results more accurate by measuring all of the potato not just the length and weight, I could have measured every face of the potato length and width, and this would have made my results extremely accurate. I could have used a more accurate scale, which went to three decimal places so that there wasn’t hardly any difference in the weight of my potato chips. I could have checked accurately that there was no trace of other substances or solutions on the beakers or measuring cylinder I used.

Henry Pearman

        There is one result which I think could be a bit anomalous and that is the 0.5m solution because I didn’t expect in to decrease in weight as much as I did I thought it would only have decrease a slight bit but there was quite a big decrease. I think that the solution could have been a bit higher concentration than 0.5 m so then the potato chips would decrease in weight more. I think I have good enough results to be certain of my conclusion apart from the 0.5m. They are good enough because there is a steady curve on the graph and the points are not very far away from each other at the intervals. The 2 potato chips in each solution are not very far away from each other in the results; there is never more than 0.2g between each result, which I think is quite accurate for my results.

        I think I could have done a few more trail runs at the start than I did so I could be certain that my experiment was going to work out well and I could change any variables before the main experiment. I think I could have done some more accurate measurements at the start like measuring all angels of the potato so the results would have been very accurate.