Possible basis for biology coursework

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  • Created on: 11-06-10 10:27
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Rebecca Davidson
Biology Coursework
Investigating Osmosis in Potato Cells
I have carried out an investigation, as part of my biology coursework, to
show osmosis happening in potato cells. Below is my method of how I
carried out this experiment.
1. Gather apparatus(McCartney bottles, measuring cylinders, salt
solution, distilled water solution, a balance, a white tile, coloured
pins, a potato, a cork borer and beakers.) The white tile will be used
to put the potato cylinders on.
2. Make up the 1.0 M salt solution, then the 0.8M solution, then the
0.6M solution, then the 0.4 solution,and then the 0.2 solution.
3. Fill one McCartney bottle with 10ml of distilled water
4. Fill the rest of the bottles with the different salt solutions.
5. Use the cork borer to create cylinders from the potato.
6. Measure and record the mass of the potato cylinders
7. Assign a different coloured pin to each cylinder, e.g. all the number
ones will have a purple pin in them, the number twos will be pink,
and the remaining three potato cylinders will maybe have white pins
in them.
8. Place 3 different coloured pinned potato pieces into the distilled
water solution. Repeat this step over and over again until all the
McCartney bottles are filled with one cylinder of each coloured pin.
9. Leave until lunchtime.
10. Remove the potato cylinders from the bottles.
11. Empty the bottles down the sink.
12. Dry the potato cylinders carefully with a paper towel.
13. Record the final mass of the cylinders using a balance.
I predict that in the distilled water solution, the potato cylinders will grow,
because of osmosis. The water concentration outside the potato cylinders
is greater than the water concentration inside the potato cylinders. To get
an isotonic concentration, the water will enter the permanent vacuole and
make the cell grow. In the full salt solution, I predict that the potato
cylinders will shrink, because of osmosis happening. The water

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Rebecca Davidson
concentration on the inside of the potato cylinders is higher than the water
concentration on the outside, so to balance it up, the water will exit the
potato cylinder, until an isotonic reaction happens. This will probably
make the potato cylinders shrink because the permanent vacuoles will be
pulling the cell menbrance away from the cell wall.
Solution table
This is the table that I made up to help me make up the solutions.
Distilled water Salt solution
0ml 0.0ml
2ml 0.…read more

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Rebecca Davidson
There have been some anomalies in my results, but the main trend of it all
is that the potato cylinders get larger, by osmosis. The water
concentration was obviously larger than the water concentration inside the
potato cylinders, so in order to balance the two out, the water molecules
have been absorbed into the cells, therefore making them bigger.…read more


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