Discovering the Lowest Concentration Of Lead Ions Needed to Cause the Loss of Partial Permeability of Cell Membranes.

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Discovering the Lowest Concentration Of Lead Ions Needed to Cause the Loss of Partial Permeability of Cell Membranes

Aim:

To discover the lowest concentration of lead ions needed to cause the loss of partial permeability of cell membranes.

The cell membrane I will use to conduct this experiment will be the outer fleshy leaves of red onions.

Background information

The plasma membrane of living cells is a partially permeable membrane, and osmosis is the principal mechanism by which water enters and leaves plant and animal cells. Whether the net direction of movement is into or out of the cells depends on whether the water potential of the cell solution is more negative or less negative than the water potential of the external solution.

When the external water potential is the same as that of the cell, there is no net movement of water in any direction. When the external water potential is less negative than that of the cell (it is surrounded by a more dilute solution), there is a net movement into the cells. The cytoplasm becomes distended by water uptake; if this distension causes pressure against a