# Osmosis in Potato Chips

Topics: Measurement, Tobias, Potato Pages: 4 (1095 words) Published: February 22, 2005
GCSE Biology: Osmosis in a Potato
Aim
To investigate the effect of placing a piece of potato in a given strength of sugar solution. Prediction
I predict that, as the solution becomes more concentrated the more the cell will shrink, as the water, of higher concentration inside the potato cells, flows down a concentration gradient into the solution, which has a lower concentration of water molecules. If we say that the percentage change when the potato is placed in the 1M solution is x%. I predict that when the solution is 0.5M the percentage change will be 0.5x%, and when the solution is 0.25M strength I hypothesise the change will be 0.25x%. Variables Description: Dependant Variables

The dependent
variable is plotted on the y-axis. In this experiment this is the change of mass of the potato when it is placed in different strengths of sugar solution. Variables Description: Independent
Variables
The independent
variable is plotted on the x axis and is what you choose to change in the experiment. In this experiement it is the strength of the sugar solution. Variables Description: Constant Variables
These stay the same all the way through the experiment and are the fair test rules. In this experiment that are that the amount of sugar solution used must always me 10.0ml. This is to be placed into the test tube. The solution needs to always be at the same temperature. We will make sure that all experiments are at 20 degrees centigrade before we start the experiment. The size of the potato sample that we place into the solution also needs to be kept constant. A mass of 2.5-2.6g is sensible. The diameter is fixed as the potato cork borer always measures to the exact same measurement. We also needs to make sure that the potato is left in the solution for the same time, 30:00 minutes. Equipment

Potato
Standard Sugar Solution
Wash Bottle
Test Tubes and Test Tube Rack
Cork Borer
Scalpel
Cutting Board
Scales accurate to 2.d.p
...