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To investigate the effect of different concentrations of sucrose solution on potato cells

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Introduction

Investigating Osmosis in Potato Cells Planning: Aim:- To investigate the effect of different concentrations of sucrose solution, on potato cells Osmosis:- Osmosis is the passage of high water concentration through a semi-permeable membrane to a region of low water concentration, i.e. the passage of water. Explanation of osmosis For osmosis to occur there must be; semi-permeable membranes are very thin layers of material (cell membranes are semi-permeable) which allow some things to pass through them but prevent other things from passing through. Cell membranes will allow small molecules like Oxygen, water, Carbon Dioxide, etc. to pass through. Cell membranes will not allow larger molecules like Sucrose, etc. to pass through. Regions of high concentrated water are either a very dilute solution of something like sucrose or pure water. In each case there is a lot of water, there is a high concentration of water. Regions of low concentrated water are a concentrated solution of something like sucrose. In this case there is much less water. If the solution surrounding the cell has a higher water concentration than the cell, the cell will gain water by osmosis. Water molecules are free to pass across the cell membrane in both directions, but more water will come into the cell than will leave. The cell is likely to swell up and become 'turgid'. If the solution is exactly the same water concentration as the cell there will be no movement of water across the cell membrane. ...read more.

Middle

* Get 2-3 reasonably sized potatoes, and an apple corer. * Cut out seven pieces of potato using the apple corer and place them in a horizontal line. * Cut each potato piece, so they are all the same length, around 2-3cm. * Make sure the potato pieces are in the same order as the solutions which are going to be used, i.e. potato piece one goes with solution A etc... * One by one weigh each piece, still keeping sure that they don't get mixed up, this process can be done using Weighing scales, or for better accuracy in weight electronic scales can be used. * Draw a table to record the results. The table could look like this:- concentration number Sucrose solution Sucrose/Water Weight Before (g) Size Before(cm) Weight After (g) Size After(cm) Change in mass(g) Size change (cm) A 30ml/0ml B 25ml/5ml C 20ml/10ml D 15ml/15ml E 10ml/20ml F 5ml/25ml G 0ml/30ml * Once all the measurements and weights have been taken on each potato piece. Then take a recording of the time and place all seven pieces of potato in its corresponding test-tube. * Now, leave the Osmosis to take place for around 15-20 minutes, we leave the experiment for 15-20 minutes because, 1. It gives more chance for osmosis to happen, 2.Better and more accurate results can be produced. * To gain an average do this test a couple of times. Fair Testing: The experiment was kept fair by ensuring that all Potato pieces got the same time in the solutions, i.e. ...read more.

Conclusion

As I said previously to improve on this I think that the test could be done again for the weight to see if the results occur to be the same EVALUATION: I feel that the overall procedure went according to plan, using the method made in the preliminary work, which we further used in the experiment worked well, we got all the main points needed to do the experiment and most of the results agreed with my hypothesis. If a trend line were to be added to the average size change graph it would be a straight diagonal line which is what should happen. Out of the graphs produced the length one was the most accurate with it showing with it showing that the potato does get smaller and become flaccid, and the opposite way round, i.e. becoming turgid in different concentrations. This was a good experiment to do, most results were accurate and it showed in presenting them. The reason some of my results were not anomalous was because that as osmosis occurs, water and sugar cross the cell membrane to level out, so the ones with no sucrose solution present became more turgid because there were no sucrose to replace some of the water, more water moved into the potato. To carry this experiment on further, the tests could be done more times to see if the results are the same, leave the potato pieces in for a longer period of time too see if this get better results, possibly use a higher concentration of sucrose or use larger potato pieces Biology Osmosis C/w Iain Riley 1 Ms. Perfect ...read more.

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