GCSE Biology CourseworkTHE EFFECTS OF GLUCOSE CONCENTRATION ON OSMOSIS IN POTATO CELLSPrepared by:Bhavin PatelTh...

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GCSE Biology Coursework

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Apparatus: -

  • Potato
  • Blade
  • Cork borer
  • Stopwatch
  • Glucose solution
  • 50cm3 Measuring cylinder
  • Electronic Balance (scale in grams)
  • Five 200cm3 beakers
  • Forceps
  • Labels
  • Water bath

Procedure: -

  • First cut the potato into half
  • Using the cork borer cut the potato to obtain five cylinders of potatoes

(Make sure that the potato cylinders are from the same potato as the potato tissues maybe different from different aged potatoes)

  • Cut the potato cylinders down to the same length
  • Measure the mass of the each potato cylinder
  • Note down all your results in the table shown below

  • Use five different concentrated glucose solutions:-
  • 2% glucose solution
  • 4% glucose solution
  • 6% glucose solution
  • 8% glucose solution
  • 10% glucose solution
  • Set up 5 beakers and pour the glucose solution in to them
  • Using a measuring cylinder, measure 20cm3 of each of the solutions and pour it into the beakers.
  • Label the beakers according to the concentration of the solutions.
  • Add the potato cylinders to the solutions
  • Immediately time the experiment for fifteen minutes(make sure that all the experiments are timed for the same period)
  • After fifteen minutes, remove the potato cylinders from the beakers
  • Wipe off any excess solution off the cylinders
  • Using the electronic balance measure the mass of the potato cylinders
  • Note the mass down in the table at the end of the first page.
  • Repeat this experiment three more times.
  • After carrying out the experiment three more times, average the results out and add them in a table similar to the one show in page one.
  • Draw a graph and plot the average results on it
  • Plot the graph as show below: -

The reason why the experiment is repeated trice is because it is to ensure that the results obtained are reliable. Temperature is a factor that affects osmosis. To avoid this to happen I will be using water bath and I will try to keep the temperature at a constant of 35 degrees.

I decided to use the concentrations I am using in the main experiment after carrying out a preliminary study. I also decided the amount of time to leave the potato cylinders in the solution after carrying out the preliminary study. More details can be found in the appendix.


Hypothesis: -

Osmosis is the net diffusion of water molecules from a region of high water potential to a region of low water potential through a partially permeable membrane. With this statement my hypothesis is that the mass of the potato cylinders will decrease because the concentration of the sugar solution outside the potato cell is higher than the one inside the potato cells. Therefore osmosis takes place and the water inside the potato cell that has a lower concentration diffuses out of the potato cell through the partially permeable membrane thus making the cell flaccid. If the amount of water particles is higher outside than inside the potato cells then the water molecules will diffuse into the cell making it turgid.

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Justification of hypothesis: -

I am sure that my hypothesis is correct because if there was no sugar solution and only distilled water, the cells of the potato will become turgid as the water diffuses into the cells. If there is more sugar than water i.e. higher concentrated sugar solution, the water in the cells will diffuse out as the cells tries to keep both its internal and external conditions the same. As osmosis is the net diffusion of water molecules, sugar molecules will not be able to move out or in to the cells. The ...

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