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Osmosis Investigation - How Does Salt Solution Concentration Affect The Mass Of Potatoes?

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Introduction

Alex Rock 10A Biology Osmosis Investigation How Does Salt Solution Concentration Affect The Mass Of Potatoes? Introduction In my investigation to find out how salt solution concentration affect the mass of potatoes, I will investigate how much the mass of a potato changes if I leave it in a beaker of water with a specified salt concentration for half an hour. I will change the salt concentration after each experiment. Background Knowledge Osmosis is the passage of water molecules from a weaker solution to a stronger solution through a partially permeable membrane. A partially permeable membrane only allows small molecules to pass through, so the larger molecules remain in the solution they originated in. When water enters a plant cell it swells up. The water pushes against the cell wall and the cell eventually contains all that it can hold. The strong cells wall prevents bursting. The cell is turgid. If plant cells lose water the cells become limp and flaccid. Water is essential for support in plants. ...read more.

Middle

I will also keep to using the same type of potato, and the time the potato is immersed in the solution will not differ. The solution's temperature will be taken before each experiment. It will always be room temperature, but I still need to ensure that my solution's temperature remains constant. Measuring The units of measurement I will use will be grams for the mass of the potato, and I will use an electronic balance to measure it. For measuring volume, I will use a measuring cylinder which specialises in millilitres, and for time I will use seconds and minutes. Time will be measured using a stopclock. Safety I will ensure that I don't drink the solution, and that I don't accidentally eat the potato. I will also wear protective gloves to ensure that the borer doesn't accidentally slip and cut me, and I will always point the borer away from me. I will not run in the laboratory, and my total concentration will always be on my experiment, so I can see where a potentially dangerous accident could occur, and I will be able to stop it in time. ...read more.

Conclusion

The reason for this is that osmosis is taking place; osmosis is the passage of water molecules from a weaker solution to a stronger solution through a partially permeable membrane. A partially permeable membrane only allows small molecules to pass through, so the larger molecules remain in the solution they originated in. Evaluation I feel that I didn't have any anomalous results, as my graph appears to be in accordance with my prediction. However, I feel that we should have made the original masses of the potatoes the same, as the potato samples used for the 6% solution experiments are nearly a gram lighter than the other potato samples. This was because we were running out of our potato supply, so we should have been more prepared. I would also have liked more results, as you can never have enough results because it is easier to draw up a more definitive and precise conclusion when a lot of results are presented. I could also have tried different types of potato to discover if one type has a saltier concentration than the other. I would also like to a wider range of salt solutions. ...read more.

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Here's what a teacher thought of this essay

4 star(s)

This is a good report on an investigation.
1. The introduction is very well written and is an opportunity to include references
2. The method, key factors and results are well presented and detailed
3. The conclusion and evaluation lack detail
**** (4 stars)

Marked by teacher Luke Smithen 24/04/2013

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