Plasmolysis Lab

Topics: Osmotic pressure, Concentration, Osmosis Pages: 3 (765 words) Published: December 19, 2012

Aim: The purpose of this experiment is to investigate the effects that the molarity of the sucrose solution and distilled water have on the plasmolisys of epidermal cells of a red onion.

Hypothesis: Taking in consideration osmosis, and my knowledge about it, my prediction is that as the molarity of the solution under which the cells are exposed will increase, also the amount of plasmolysed cells, counted from amount of undamaged cells taken into account, will also increase. Hence, theoretically, the amount of plasmolysed cells in distilled water should be 0, while at 1mol solution, all of the relevant cells should be plasmolysed. This is so, because plasmolisys occurs due to loss of water through osmosis, which depends on the concentration difference, and consists in the movement from a high to a low concentration gradient. This suggests that on a high molarity, the amount of water present outside the cell is lower than inside the cell, therefore it will move out of the cell, causing a loss of water. There are also other substances which might diffuse out or in, but water is the most relevant one for the sake of this lab work.

Variables: independent- molarity of substance
dependent- percentage of plasmolyzed cells
controlled- same type of epidermal cells, same method

Materials: microsope, razor blade, petri dish, 7 tubes with stoppers, distilled water, sucrose solution, red onion.

Method: (see appendix)

CHANGES: - we used distilled water, hence 7 tubes, and two more pieces of epidermis

The data was recorded with a table, and for each of the different solutions, only one measurement was made, due to limited amount of time. Hence, my own data will be grouped with my classmates', in order to achieve more reliable and precise results.

Raw Data:

Amount of Plasmolyzed cells counted from amount taken into account, under solutions with different molarity.

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