Aim: To estimate the solute potential of a plant tissue.

Conclusion:

        The results of the investigation show that the greater the molarity, the more plasmolysed cells will appear.  Plasmolyses is the shrinkage of volume of a cell.  This is caused by the falling of water concentrations and ultimately results in the contraction of the membrane.  The most contracted membranes were found in epidermal cells that were left in the solution with the greatest molarity; in this case it was the cells that were left in the solution with a 1.0 molarity.  The graph shows a constant start.  It very quickly shoots up, with a huge leap from .6Mto 1.0M.

        The results for this experiment did not come back exactly the way they should have to prove the point.  In the epidermal cells that were placed in the .3M solution .01% of the cells plasmolysed, but in the epidermal cells that were placed in the .4M solution 0% of the cells were plasmolysed.  If the experiment had gone exactly as planned, the cells that were placed in the .4M solution would have had more than .01% cells plasmolysed.  However, in the overall view, the cells that were placed in the .3M solution came back with .01% of the cells plasmolysed and the cells that were placed in the 1.0M solution had 80% of the cells plasmolysed.

        Some of the major inaccuracies that have to be mentioned about this investigation are that part of the procedure that was changed was the time.  Instead of the epidermal cells being left in the solutions 20 minutes, they were left for a day.  Not only, were they left much longer, but the molarity of the solutions could have also changed since they were left uncovered for over 24 hours and some of the water could have been evaporated.  Another factor that contributed to the errors in this investigation was that all of the data was approximated.  Every single cell that appeared in the microscope was not accounted for and therefore all collected data is not exact, but instead a rough calculation.  Another error that could have occurred, and that would explain what happened to the cells that were put in the solution with .4M, is that onion skin dried out before it was placed in the sucrose water.  Also, there could have been a variation between the different onion epidermis cells that were used, because not all cells in the same tissue have the same solute potential.

Next time, to avoid these errors, the correct time should be used.  The pieces of onions should be cut more exactly and each cell that is visible through the microscope should be counted. To evade to possibility of the onion cells drying out they should be immediately placed into the sucrose solution.  Also, during the waiting period the solutions that the cells are in should be covered, as to avoid any evaporation that may occur.