Investigating Osmosis in Potato Tissue.

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Investigating Osmosis in Potato Tissue

Aim

  To estimate the concentration of sucrose in potato tissue.

Hypothesis

  I believe that the potato tissue that has been in the hypotonic (0.1M sucrose) solution will be more turgid than before, while the tissue in the isotonic (0.3M sucrose) will be similar to its previous state.  The tissue that has been in the hypertonic (0.5M sucrose) should be far more placid than it was before.  This is because of osmosis – water diffusing in and out of the potato tissue cells.

Apparatus

  • 1 potato tuber                                                  
  • 1 cork borer
  • 1 ceramic tile
  • 1 scalpel
  • Paper towels
  • 6 boiling tubes
  • 1 marker pen
  • 0.1M, 0.3M, and 0.5M sucrose solution
  • Access to an electric balance
  • 1 funnel

Method

  The volume of each boiling tube was calculated, and then 2 tubes were half-filled with 0.1M sucrose solution, 2 tubes were filled with 0.3M sucrose solution, while the final 2 tubes were filled with 0.5M sucrose solution.  Then 6 cylinders of potato were cut from the tuber using the cork borer.  These were then all cut down to 20mm in length using the scalpel.  They were then dried with the paper towel to remove excess water before being weighed on the electric balance.  The weight of each was recorded.  They were then all immersed in the solution in the boiling tubes, and the tubes were labelled using the marker pen and then lids were put on.  They were then left for 24 hours in a moderate temperature before being taken out and dried using the paper towels.  They were then weighed on the electric balance and the final mass was recorded.  The cylinders were then gently squeezed to determine the condition of the potato tissue after osmosis – very firm (turgid), firm, or soft (flaccid).  The percentage difference between the mass before and after the experiment was then calculated, and the class results were pooled.

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Results

Table showing our Results

Table showing the Class Results

Conclusion

  We can see from our results that the concentration of sucrose in the solution affects the change in mass of the potato cylinders.  In the 0.1M sucrose concentration (hypotonic solution) the cylinders gain 17.3% in mass.  In the 0.3M (isotonic solution) the cylinders gained just 4.1% in mass on average, while in the 0.5M (hypertonic solution) the cylinders lost 10.3% of their mass on average.  This trend suggests that the lower the concentration of ...

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