Introduction and Hypothesis
Osmosis is the net movement or diffusion of solvent through a selectively permeable
membrane from a region of low solute concentration to a region of high solute concentration.
Hypertonic, isotonic, and hypotonic are three words to describe the net movement of water in
and out of the cell with hypertonic being net movement of the solvent moving out of the cell,
hypotonic being net movement of the solvent moving into the cell, and isotonic meaning the net
movement of solvent in and out of the cell are equal. Plasmolysis is the process in which cells
lose water in a hypertonic solution, resulting in the plasma membrane pulling away from the cell
well.
Question: How would an increase in glucose concentration affect the plasmolysis in red onion
cells?
Hypothesis: As glucose concentration increases, the amount of plasmolyzed cells will also
increase.
Prediction of Hypothesis: A greater glucose concentration will cause the ratio of plasmolyzed
cells to total number of cells to increase.
Null-Hypothesis: As glucose concentration increases, the amount of plasmolyzed cells will not
be affected
Prediction of Null-Hypothesis: A greater glucose concentration will not cause a change in the
ratio of plasmolyzed cells to total number of cells. They will have virtually the same percentage.
Experimental Set-Up
Start by obtaining a wedge of one petal of a red onion. Peel the epidermal layer from the
purple side of the onion and place it flat onto a glass slide. Then place a cover slip over the
