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  • Level: GCSE
  • Subject: Science
  • Document length: 1548 words

Data Analysis - Osmosis in Potatoes

Extracts from this essay...

Introduction

G.C.S.E. Biology Data Analysis - Osmosis in Potato Chips Contents Page 1. Aim.............................................................................................................. 3 2. Results........................................................................................................ 3 2.1 Tables 2.2 Graphs 3. Analysis....................................................................................................... 5 4. Evaluation................................................................................................... 6 5. Conclusion.................................................................................................. 7 6. Bibliography................................................................................................ 8 1. AIM The purpose of this experiment was to analyse the effect of osmosis in potato chips (cut slices) and then be able to explain the significance of this in the human body. I predicted that as the concentration of the solute was increased, the mass of the potato would decrease because of osmosis. 2. RESULTS 2.1 Tables Potato No. Concentration (M) Start mass (g) Finish mass (g) Change in mass (g) % change in mass Average % change in mass A1 0.0 1.79 2.01 0.22 12.29 9.68 A2 0.0 1.79 1.94 0.15 8.38 A3 0.0 1.79 1.94 0.15 8.38 B1 0.5 1.79 1.86 0.07 3.91 5.40 B2 0.5 1.79 1.93 0.14 7.82 B3 0.5 1.79 1.87 0.08 3.91 C1 1.0 1.79 1.79 0.00 0.00 -0.56 C2 1.0 1.79 1.78 -0.01 -0.56 C3 1.0 1.79 1.77 -0.02 -1.12 D1 1.5 1.79 1.75 -0.04 -2.23 -5.96 D2 1.5 1.79 1.63 -0.16 -8.94 D3 1.5 1.79 1.67 -0.12 -6.70 E1 2.0 1.79 1.58 -0.21 -11.73 -10.61 E2 2.0 1.79 1.62 -0.17 -9.50 E3 2.0 1.79 1.60 -0.19 -10.61 2.2 Graphs 3.

Middle

The water in a plant cell is stored in its vacuole (see Figure 2). Figure 2: The term turgid refers to the swelling up of a cell because it has gained too much water as a result of osmosis while the term flaccid refers to the shrivelling up of a cell because it has lost too much water as a result of osmosis. In distilled water (0.0M), potato cells can become lysed, meaning that they are so turgid that they burst due to the overwhelming water pressure on the cell membrane. In concentrated solutions such as 2.0M, potato cells can become plasmolysed, meaning that they are so flaccid that their cell membranes completely leave the cell wall due to lack of water pressure on it (see Figures 3 & 4). I believe both occurred in my experiment, which would explain the curve in the line of best fit. Figure 3: Figure 4: Osmosis is of prime importance in humans and all other living organisms because it is necessary for homeostasis, the ability of the body to regulate its internal environment and maintain equilibrium. Living cells of both plants and animals are enclosed by a cell membrane which regulates the flow of liquids and of dissolved solids and gases into and out of the cell through the process of osmosis.

Conclusion

It is probably due to human error or environmental changes. I can prove that D1 was the outlier rather than D2 or D3 by removing it from the data set and recalculating the average for the remaining measurements, a method known as a best estimate. The best estimate percentage increase in mass for chips D2 and D3 equals -7.82%, which is much closer to the trend line. If I was to do this experiment again, I would make a number of changes to my method to improve my results. Firstly, I would take more repeat measurements because this would give me a more accurate representation of the average. I would also take greater care when handling the potato chips so that they did not lose water as they were taken to be weighed. Finally, I would want to work in a more controlled environment than a classroom, as the temperature of the room can have an effect on the speed of osmosis. 5. CONCLUSION In conclusion, this experiment has shown that increasing the concentration of the solute (in this case salt) decreases the mass of the potato chips. I am generally confident with the results, but I would recommend that further work to investigate how long it would take before the solutions reached equilibrium (see Figure 5) at different concentrations should be taken in order for me to build a comprehensive understanding of osmosis. Figure 5: 6.

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5 star(s)

Response to the question

An excellent piece. Whilst the introduction could do with some minor points which are described below, the main body of text including the evaluation and analysis are done to an exceptional standard including accurate scientific reasoning behind their results. ...

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Response to the question

An excellent piece. Whilst the introduction could do with some minor points which are described below, the main body of text including the evaluation and analysis are done to an exceptional standard including accurate scientific reasoning behind their results. The candidate conveys scientific concepts with clarity and the whole piece is done to a much higher standard than I would expect for GCSE level.

Level of analysis

The aim is set out concisely and tells us exactly what the candidate is intending to do, but it lacks some definite information on the experiment because the candidate does not say if the concentration of solute is at the outside or inside the potato and so forth, so it would be hard to grasp the clients meaning, so they should state this more clearly. The candidate did not include a method which should have been included as it makes it harder to interpret their results table. Also, if a method was included, the candidate could have discussed the factors which may have affected the experiment and how they avoided this which would show their understanding of the experiment and of osmosis. The candidate includes a well labelled clear graph which is very good to see. The candidate analyses the experiment very well in their analysis showing great scientific depth in their thinking and using very good images to support their text. The candidate suggests some improvements in their evaluation, but I would like to see a couple more errors and considered improvements and how the errors may have affected the experiment for them to get a higher mark. The candidate shows thinking in how they could expand on the experiment which is very good for GCSE level.

Quality of writing

The letters in the introductory page are all jumbled up, but this could be due to the width of the PDF file. Spelling, grammar and punctuation to a high standard. Layout flows well and looks professional.


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Reviewed by skatealexia 11/07/2012

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