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An experiment to show the movement of water into and out of plant cells to discover the concentration of the cytoplasm

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Introduction

An experiment to show the movement of water into and out of plant cells to discover the concentration of the cytoplasm By Karamveer Singh Aulak Aim I am investigating the effect of osmosis on a potato through the concentration of the cytoplasm in a potato cell. I am going to find out this by using salt solutions. Osmosis is the diffusion of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration. Prediction I predict that the higher the concentration of salt in the solution, the more water will move out of the potato cell. We know that osmosis is the flow of water in a solution through a membrane while the other molecules are unable to pass through the membrane. Some membranes may allow all or none of the molecules of a solution to pass through, only a few may allow a selective flow. The cell membrane of the potato is partially permeable (it lets some substances in but not all substances). This means that water particles can diffuse into the cells, via osmosis. This occurs if the cells are surrounded by a weak solution e.g. water. If the cells are surrounded by a stronger solution, e.g. salt water, the cells may lose water by osmosis. 1 molar- this will take most of the water out this is because the salt solution is strong. I also think the potato will become lighter because the salt solution is pushing some of the water out until the concentrations are the same . The weight will drop the most because of how much water is being lost, the length will change the most because of how strong the solution is. The diameter will drop by a considerable amount. 0.75 molar- this rather strong solution will push water out enough to make it become flaccid. ...read more.

Middle

Results Table Here is my results table I have made it easier to show by the differences from before and after along with a simple calculation which will explain all of this. Length Results Solution Length Before (mm) Length After Calculation Difference Percentage (%) 1 molar 50 42 50-42 -8 16 0.75 50 46 50-46 -4 8 0.5 50 48 50-48 -2 4 0.25 50 47 50-47 -3 6 0 50 52 52-50 +2 -4 I found out that all lengths had decreased up to 8m. 0 molar had actually increased in lengths this can be explained simply because the potato cylinders have swelled up this is because water has entered their cells by osmosis causing it to become turgid. This all can be backed up by my scientific knowledge. The reason why salt solutions have shrunk in size is because water leaves their cells due to osmosis, this again can be backed up in my scientific knowledge. Mass Results Solution Mass Before (g) Mass After Calculation Difference Percentage (%) 1 molar 3.20 2.30 3.20-2.30 -1 28 0.75 3.55 2.70 3.55-2.70 -0.85 23 0.5 3.35 2.35 3.35-2.35 -1 29 0.25 3.75 2.50 3.75-2.50 -1.25 33 0 3.15 3.30 3.30-3.15 +0.15 -4 The Mass had increased for 0 molar by 0.15g this is as similar as the reason for length. It increased because when the water concentration is lower in the tissue, the water will go inside the tissue of the potato, and the potato will gain weight. The weight for all salt solutions has increased by up to 1.25 this is because potato has shrunk from earlier (length results) because water leaves its cells due to osmosis happening. The water will get pushed out by the salt solution this will happen until the water and the salt solution are equal meaning that it has gone lighter and has lost weight. This can also make it feel flaccid. ...read more.

Conclusion

To study osmosis to a more deeper extent may be we could of used a variety of potato's or even different foods e.g. carrots. Seeing osmosis in action in different cells would help gain more knowledge. Changing the variables completely instead of using a salt solution we might use a sugar solution to see how the potatoes cells react with different solutions. To do an experiment without making it fair is useless what is the point of even doing it ? Even when it came to weighing the potato on the balance I wait till it got to 0 otherwise more false results would of come out. I tried to do the experiment with as little faults as possible, I did succeed to a limit with a few anomalous results along the way. I tired to make it fair by not using a different brand of potato's, also by using the same Cork Borer. I tired to measure with as much accuracy as possible and weighing and measuring the potato properly . We could also of used better measuring cylinders because the ones provided were a bit old and had scratches on them so it was hard to see how accurate the solutions were being poured. Also use a more accurate measuring balance because the one we were using was old, some potato's weight might of been effected because water might of been left on by potatoes dripping in the solutions. This could of been avoided if we had enough time to do the experiment so we could of done it 1 potato at a time so instead of wiping about 5 potato's on 1 paper towel but this way would be very time consuming. We could of used a test tube instead of a petri dish this would help by observing better. This wasn't possible in our case because supplies were limited. After all I have learnt in this experiment I think that I have learnt enough to carry out the experiment again and make it better with out the faults the first time. ?? ?? ?? ?? ...read more.

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