An Investigation to Find out the Solute Concentration of Potato Cells by Osmosis.
Background information
Here is a definition of osmosis:
* Osmosis is the net flow of water through a selectively permeable membrane.
In this investigation we will be watching osmosis at work on potato cells and different concentrations of sucrose.
Plan
Variables Available to Test
* Temperature - Temperature could be a main factor as it could speed up the movement of the water molecules, and therefore speed up osmosis.
* Size of Potato - The size of the potato could effect the amount of water molecules that are able to diffuse through into the surrounding sucrose solution.
* Sucrose Concentration - The sucrose concentration, if high would allow more water molecules through and, if low wouldn't let many molecules through at all. Osmosis only works if the surrounding sucrose solution concentration is higher than the concentration the molecules start in.
We chose to use sucrose concentration to investigate osmosis, as osmosis is mainly to do with diffusing from one concentration to another.
Method
. Peal a potato using a knife but remember to push the blade away from you, because if you slipped then you could cut yourself.
2. Using a corer cut out cylinder shaped pieces from the potato. Make sure you use the same sized corer each time so you don't get different sized potato pieces.
3. Measure out the pieces to the length you want (3cm).
4. Work out the surface area of the potato piece using this formula:
2((r²) + h (2(r)
5. Weigh the potato piece on a high accuracy scales, at least to 2 decimal places.
6. Measure out 5 boiling tubes with a different sucrose concentration in each one. We used 16ml of a mixture between water and a 20% sucrose concentration, depending on which concentration you needed, for example if you wanted to use 5% sucrose concentration you would use 4ml of the 20% sucrose concentration and 12ml of water. We decide to use 16ml of sucrose solution because it is divisible by 4 and would make it a lot easier to sort the ratio of sucrose to water out. Use one boiling tube with 0% sucrose concentration, one with 5%, one with 10%, one with 15% and one with 20%. For 0% sucrose concentration use 0 sucrose concentration, just water, for 5% sucrose concentration use 4ml of the 20% sucrose concentration and 12ml of water. If you wanted to use 10% sucrose concentration use 8ml of the 20% sucrose concentration and 8ml of water, if you wanted 15% sucrose concentration use 12ml of 20% sucrose concentration and 4ml of water. Finally if you wanted to use 20% sucrose concentration use 16ml of 20% sucrose concentration and no water.
Background information
Here is a definition of osmosis:
* Osmosis is the net flow of water through a selectively permeable membrane.
In this investigation we will be watching osmosis at work on potato cells and different concentrations of sucrose.
Plan
Variables Available to Test
* Temperature - Temperature could be a main factor as it could speed up the movement of the water molecules, and therefore speed up osmosis.
* Size of Potato - The size of the potato could effect the amount of water molecules that are able to diffuse through into the surrounding sucrose solution.
* Sucrose Concentration - The sucrose concentration, if high would allow more water molecules through and, if low wouldn't let many molecules through at all. Osmosis only works if the surrounding sucrose solution concentration is higher than the concentration the molecules start in.
We chose to use sucrose concentration to investigate osmosis, as osmosis is mainly to do with diffusing from one concentration to another.
Method
. Peal a potato using a knife but remember to push the blade away from you, because if you slipped then you could cut yourself.
2. Using a corer cut out cylinder shaped pieces from the potato. Make sure you use the same sized corer each time so you don't get different sized potato pieces.
3. Measure out the pieces to the length you want (3cm).
4. Work out the surface area of the potato piece using this formula:
2((r²) + h (2(r)
5. Weigh the potato piece on a high accuracy scales, at least to 2 decimal places.
6. Measure out 5 boiling tubes with a different sucrose concentration in each one. We used 16ml of a mixture between water and a 20% sucrose concentration, depending on which concentration you needed, for example if you wanted to use 5% sucrose concentration you would use 4ml of the 20% sucrose concentration and 12ml of water. We decide to use 16ml of sucrose solution because it is divisible by 4 and would make it a lot easier to sort the ratio of sucrose to water out. Use one boiling tube with 0% sucrose concentration, one with 5%, one with 10%, one with 15% and one with 20%. For 0% sucrose concentration use 0 sucrose concentration, just water, for 5% sucrose concentration use 4ml of the 20% sucrose concentration and 12ml of water. If you wanted to use 10% sucrose concentration use 8ml of the 20% sucrose concentration and 8ml of water, if you wanted 15% sucrose concentration use 12ml of 20% sucrose concentration and 4ml of water. Finally if you wanted to use 20% sucrose concentration use 16ml of 20% sucrose concentration and no water.
