If you order your research paper from our custom writing service you will receive a perfectly written assignment on osmosis. What we need from you is to provide us with your detailed paper instructions for our experienced writers to follow all of your specific writing requirements. Specify your order details, state the exact number of pages required and our custom writing professionals will deliver the best quality osmosis paper right on time.
Our staff of freelance writers includes over 120 experts proficient in osmosis, therefore you can rest assured that your assignment will be handled by only top rated specialists. Order your osmosis paper at affordable prices
Osmosis Coursework
Planning
Aim
The aim of our experiment is to find out how the strength of a sugar solution affects potato cells through osmosis.Order custom research paper on osmosis
Method
1.Cut out potato chips, making sure every piece is skinless, the same length (40mm) and the same diameter (6mm). The length was measured with a ruler and a bore was used to ensure the diameter was consistent.
.Mix up distilled water and 1.0M sugar solutions, to make mixtures with known molar contents using measuring cylinders.
Volume 1.0M Sugar solutionVolume distilled waterMolar Content
50.0ml0.0ml1.0
7.5ml1.5ml0.75
5.0ml5.0ml0.5
1.5ml7.5ml0.5
0.0ml50.0ml0.0
.Put a single potato chip in with 50 ml of each solution.
4.Leave for sufficient time for osmosis to happen. How long is needed will be determined in a preliminary investigation.
5.After leaving measure lengths of the potato chips to see if this has changed.
6.Calculate percentage length change.
To make this a fair test it is important to ensure that the chips are all identical in size and shape and that the same amount of solution is going is used in each tube. The length of time the chips are in the solution might be an important factor so in comparing results we will only compare tests where the time is the same. Another thing that might vary is the individual potato, so for each set of tests the same potato was used for each solution strength.
The size of the potato chips was chosen to be 4cm long and 6mm diameter because they are completely submerged by 50 ml of fluid in a test tube and will fit in the diameter of the test tubes.
Apparatus
•Multiple test tubes
•Test tube rack
•Scalpel
•Accurate ruler (to mm)
•mm radius bore
•Distilled water
•1.0M Sugar Solution
•Beaker
•Measuring Cylinder
Prediction
Each cell of the potato is surrounded by a semi permeable cell membrane. Semi permeable means that water molecules can travel through the membrane while sugar molecules cannot because they are too large. This will mean that over a period of time water will diffuse through the membrane from a weaker solution to stronger solution. Where the cells are in a weaker solution than that of the cells' cytoplasm I would expect the cells to loose water by osmosis and the cytoplasm to shrink. Where the concentrations are the other way round I would expect the cells to take on water through osmosis and the cytoplasm to expand.
When we measure the length of the chips this is really a way of measuring the size of all the cells in one go.
Not all cells will be in the solution as they might be in the centre of the potato chip. I don't think this will affect the experiment because I would expect water to pass from cell to cell in the chip through osmosis.
In the experiment we used sugar in the solution. Sugar is a large molecule in comparison with water and I would expect that it would not be able to diffuse through the semi permeable cell membrane. This means water is able to travel in and out of the potato's cells while sugar cannot. A strong sugar solution has a lower concentration of water than a weak sugar solution so the water will diffuse from the weak solution to the stronger solution. Eventually all the solution strengths will equalise so that everywhere has an equal strength of sugar solution. When everywhere has the same sugar strength this process stops. This means that given sufficient time the growth there is only a certain amount the chips can grow or shrink.
I predict that if the concentration of sugar in the liquid surrounding the potato chip has a higher sugar content than inside the potato then the chip will shrink as all the cells in it shrink. Once the concentrations inside and outside the cells are the same no further shrinkage will occur. This is because the water will diffuse through the cell wall in an attempt to dilute the surrounding sugar.
In concentrations of sugar less than inside the potato the potato cells will take on water and as they expand the size of the chips will increase.
Preliminary Investigation
In our preliminary investigation we put one 40mm strip of potato in each test tube, the potato was also had a radius of mm. We only used three test tubes, using just water, 0.5 m sugar, and 1.0 sugar because of time restrictions. We left the tubes for just 15 minutes, hoping this would be long enough.
Solution StrengthLength Before SoakingLength After Soaking
Water (0.0 m)40mm44
Weak Sugar Solution (0.5 m)40mm4
Strong Sugar Solution (1.0 m)40mm41
From looking at the preliminary results I'd collected, I was acutely worried. Either my prediction was very wrong, or our group had chosen a potato with a very high sugar content. I decided after viewing other group's results that it must be an abnormally sweet potato because other groups results seemed to match my prediction, therefore I feel it's unnecessary to change my prediction at this point.
Results
These tubes were left for thirty minutes, we chose thirty minutes because we thought if we left it for fifteen minutes the results may not be varied enough to get a good looking graph.
MolarStrengthLength after 0 minutesPercentage increase in length
Test 1Test Test AverageTest 1Test Test Average
1.08mm8mm8mm8mm-5%-5%-5%-5%
0.758mm8mm8mm8mm-5%-5%-5%-5%
0.58mm8mmmm8.mm-5%-5%-.5%-4.17%
0.58mmmmmm8.67mm-5%-.5%-.5%-.%
041mm4mm41mm41.mm+.5%+5%+.5%+.%
After viewing these results, our group decided the change in length was not large enough to accurately analyse results given that we could only measure the length to 1mm accuracy. We repeated our experiment, this time leaving it for 48hours.
MolarStrengthLength after 48 hoursPercentage increase in length
Test 1Test Test AverageTest 1Test Test Average
1.0mmmm5mm.mm-17.5%-0%-1.5%-16.67%
0.756mm6mm5mm5.67mm-10%-10%-1.5%-10.8%
0.57mm7mm6mm6.67mm-7.5%-7.5%-10%-8.%
0.540mm40mmmm.67mm-0%-0%-.5%-0.8%
040mm4mm41mm41.00mm+0%+5%+.5%+.5%
Note to examiner The results here are not to a degree of accuracy ofdecimal places because rulers can only go to millimetres, and no one in our group had eyes able to pinprick the exact decimal of the chip's length.
Analysis
The results show that in strong sugar solutions the chips shrink while in distilled water they actually increase in length.
The results between the individual tests are not that consistent so I have worked out average across the tests. I have also worked out the results as percentage increase in length.(both shown in the tables in the results). I have plotted the average percentage change in length of the chips against the solution strength for the 0 minute experiment and the 48 hour experiment.
Both graphs show that the stronger the sugar solution used, the more the potato chips will shrink in length. In distilled water the potato chips actually increase in length. This means that there is a negative correlation between the size of the chips after the experiment and the strength of the sugar solution used. The graph for the 48 hour experiment shows the negative correlation most clearly.
From the graph labelled 'Graph showing % length change in chips for half an hour' we can that the chips don't ever loose more than 5% length with quite a distinct curve on the graph as 5% loss is neared. This may be that the cells can only loose water at a certain rate and that enough time was not allowed
The graph labelled 'Graph showing % length change in chips for 48 hours' shows a much higher shrinkage of the potato chips and also shows a better straight line. The results for distilled water and 0.5M sugar solution are quite similar in the 48 hour and 0 minute experiment, given the accuracy it was possible to measure, while the stronger solutions showed a lot more shrinkage in the 48 hour test. This is consistent with the potato only being able to loose a maximum amount of water in a period of time.
Conclusion
The results show clearly that the length of potato chips is affected by the strength of the sugar solution they are put in. The way the chips shrink in strong solutions is consistent with the cells of the potato loosing water through osmosis and shrinking so that the chip becomes smaller. Similarly the way chips in distilled water, increase in length is consistent with the cells of the potato gaining water through osmosis and expanding to make the chip longer.
I can see there is a certain point where the sugar content of the solution is the same as the potato's sugar content, (This is where the line of best fit crosses the strength of sugar solution axis). From looking at this graph I would guess the potato's average sugar level is about 0.m. Biology for You says, "Osmosis is a particular type of diffusion involving water molecules." It also says, "The water is in fact diffusing from the weaker solution (high water content), into the stronger solution (low water concentration)"
As I predicted, if the concentration of sugar in the liquid surrounding the potato chip has a higher sugar content than inside the potato then the chip will shrink.This prediction appears to have proved correct. I can see this on the graph where the chips were left for forty-eight hours that once the line of best fit passes a certain point, the chips must have began to grow. They have grown or shrunk because water has diffused though the potato's semi permeable membrane to dilute where the higher sugar content is. This shows my results are in line with my prediction.
Evaluation
Measuring the length of the potato chips is an easy way of investigating the effect of osmosis on the size of plant cells. I think it would have been far more difficult if we'd had to look at them under a microscope.
In our raw results there is quite a large scatter, they were not consistent in across the different tests. I don't think this affects my conclusion because after averaging the graphs showed clear trends. The anomalies were probably due to the difficulty in measuring accurately, or perhaps that different parts of the potato did different things.
If I was to redo the experiment I would improve it by
•Using longer chips, so the percentage size change would be easier to measure.
•Supplement measuring by length with another measure, for example I could weigh the chips, using an accurate scale, to see if they'd lost or gained water.
•Use a more accurate device than a ruler to measure the chips.
•Use more than 5 different concentrations of sugar solution to give more results on the graph.
•Use a titration pipette to make up the solutions more accurately
I think the results my group and I have gathered show a reasonable level of accuracy. This is because they tie in with what I predicted from my scientific knowledge, and the quotes I have taken from Biology for you.
To do further research into this topic which is relevant to the investigation, we could
•Measure different potato's sugar contents to see how it compared with the solution strength where no change in length was measured
•See how different breeds of potatoes sugar contents differ.
•Try different solutes to sugar to see which give the best results.
•Look at cells under a microscope in different sugar concentrations, to see their visible differences (see if the cells were plasmolysed).
•Try and find a way of measuring turgidity of the cells, perhaps by seeing how 'bendy' the chips are.
Please note that this sample paper on osmosis is for your review only. In order to eliminate any of the plagiarism issues, it is highly recommended that you do not use it for you own writing purposes. In case you experience difficulties with writing a well structured and accurately composed paper on osmosis, we are here to assist you.Yourpersuasive essay on osmosis will be written from scratch, so you do not have to worry about its originality.
Order your authentic assignment and you will be amazed at how easy it is to complete a quality custom paper within the shortest time possible!
