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Osmosis Experiment

Extracts from this document...

Introduction

OSMOSIS EXPERIMENT AIM My aim is to see how osmosis affects the potato sap in potato cells when using sucrose solution of different strengths, and to use this to determine the strength of cell sap in potato cells. BACKGROUND Osmosis is movement of water from a weak solution to a strong solution through a semi permeable membrane. A plant cell makes most of its water in its vacuole and cytoplasm. Plants use osmosis to move water through their cells. The cell membrane is partially permeable so this means that only small particles can get through the membrane. Cell sap is a solution made of sugar and other solutes in the vacuole. The cell sap is a strong solution. If the cell is placed in water it will let water move into the vacuole by osmosis. If the cell is placed into a strong sugar solution it will shrink because the water will move into the outside of the cell by osmosis. Plant cell in strong solution: (Strong solution) H2O H2O (Weak solution) This diagram shows that the plant cell is in a strong solution so the process of osmosis here is to move water from a weak concentrated area to a stronger concentrated area which causes the plant cell to shrink and becomes flaccid. ...read more.

Middle

What would happen if a potato chip were placed into a solution of equal strength to the cell sap? If the solution were the same strength as the cell sap inside the plant cells vacuole, then water would not move in and out of the cell at equal rates, and so the potato chip would stay the same size. What would happen if a potato chip were placed into a strong solution? The potato chip would become smaller because the water inside would diffuse out by osmosis into the surrounding solution. This will give a trend like the one shown in the following graph. + Size of potato chip 0 - 0.0 0.5 Water Weak Strong Solution Solution This graph shows what I predict the graph is going to look like when I gather the results and make a graph from it. At the point where the arrow is the strength of the cell sap is equal to the strength of the sucrose solution on the line of best fit. The experiment should allow me to determine the exact strength. FAIR TEST To make my experiment a fair test I must control all the factors, which could affect my experiment and give inaccurate results. These factors are: * Strength of the solution * Volume of the solution * Length of the chip * Temperature How I am going to ...read more.

Conclusion

I think that my prediction is right although my results were not close to the line of best fit; it proves if the potato chip was placed in a strong solution it would start to shrink (flaccid) Example: (Strong solution) H2O H2O (Weak solution) And this also shows that if a potato chip is placed in a weak solution it becomes larger (turgid) EVALUATION The experiment went well but my results could have been more accurate and reliable if I repeated the experiment more than twice and took the average percentage of the result tables; I could also take the results to 2 decimal places to get more accurate results and I could have improved my results and make them more accurate if I kept the lengths of the potato chip the same at both experiments. The reason for my results to come out inaccurately is because it could have been a human error such as not reading the size of the potato chip properly, and not measuring the amount of sucrose solution added onto the potato chip. I think my results are not reliable enough to give me a firm conclusion because the experiment was carried out on bases, which could make factors produce inaccurate results. Therefore to improve the experiment I could repeat the experiment by making more than two people carry out the experiment, check the amount of sucrose solution added to the potato chip, take the measurement of the actual chip twice. ...read more.

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