Investigating Osmosis Using Potato Cylinders

In my experiment I will be testing Osmosis with a potato in relation to the solution that it is in, one solution will be pure water, the second will be  a 5% glucose concentration, and then the next a 10% glucose concentration, and then a 15% glucose concentration.  My hypothesis and the experiment will predominately affected by the type of solution that the potato cylinders are in, i.e. the solution that the potato cylinders are in will affect the results, that is whether the potato cylinders shrink, stay the same size, or grow larger:

Hypertonic Solutions: In a hypertonic solution the solution will have a higher solute concentration that the potato would, when the potato is placed inside this kind of solution water will diffuse out of it, in to the solution causing it to shrivel.

Hypotonic Solutions: In a hypotonic solution the solution will have a lower solute concentration that the potato (or any plant placed into it), when the potato is placed into this sort of solution, more water will flow into it than will flow out causing the plant/potato to become turgid; with the risk of it exploding.

Isotonic Solutions: In a Isotonic Solution, water concentration, and solute concentration are equal in the solution and in the plant/ potato. A dynamic equilibrium will exist between the number of water molecules entering and leaving the cell. The plant in this case will retain its size.

Hypotheses:  I hypothesis that when the potato cylinder is in the solution of distilled water it will not change size as the distilled water solution is a Isotonic solution, and as outlined in my introduction the net movement from the solution to the potato will be the same. In the solution of 5 and 15 I hypothesise that the size of the potato cylinder will decrease as these solutions are hypertonic and thus, the sugar content in the solution is greater than that of the sugar content inside the potato, causing water to flow out of the potato and into the solution

Apparatus: 

1. Cork Borer.
2. Scalpel.
3. Ruler.
4. 4beakers.
5. 4 varying solutions sugar/water.
6. Electrical balance

Method:

1. Peel one large potato.
2. Push borer fully into the potato, withdraw, push smaller borer into the larger borer to remove potato cylinder.
3. Repeat step 2 in order to create 10 cylinders.
4. Measure and record the volume of each cylinder
5. Place different solution into different beakers, and record which solution is in which beaker.
6. Placer a cylinder into a solution, and leave to rest for 30minutes
7. After 30 minutes has passed take out the cylinders and record the changes in size and in weight.

Variables:

Independent Variable: 

1. Concentration of glucose in water

Dependent Variable:  

1. Eventual mass, weight and size of potato cylinder, at the end of experiment.

Controlled Variable:

1. Volume of solution used
2. Time that potato cylinders are left in the solution
3. The size, mass and weight of the potato cylinders.

Fair Test: 

I am going to make my test fair by- leaving the potato cylinders in the solution for the same amount of time by doing this I will make sure that the results are relative and that all cylinders have the same amount of time to OSMOSE, I will also try and make my potato cylinders as close in size as possible, this will further the relativity and congruence that I hope to achieve in my results. Because I am checking the affect of osmosis on the weight and size of potato cylinders I will keep the potato cylinder size the same but change the concentration of sugar in different solutions to see how it affects the cylinders.

Results:-