ll plant cell membranes are partially permeable, which means they allow some substances to penetrate them but not others. Whether water enters the cell by osmosis will depend on the balance between inside and outside water potentials. If the solutions on each side of the partially permeable membrane are equal, then there will be no movement of across the membrane. This is called equilibrium and the solutions are called isotonic.
When lead nitrate is enters a cell it can inhibit the carrier proteins by non-competitive, this can damage the partial permeable cell membrane. If the membrane of a cell is damaged osmosis can't occur which will eventually kill the cell by plasmolising it.
Plasmolysis is the separation of the plant cell from the cell wall because of water loss. As water leaves the vacuole the amount of cytoplasm decreases while the cell itself hardly changes. Plasmolysis can be caused by putting a plant cell into a sugar solution such as 1molar sucrose solution, so that water is lost by osmosis. If a plant cell is put into a 1molar sucrose solution, the cell contents separates from the cell wall. This happens because the sucrose solution that has passed freely through the cell wall and has to go through the cell membrane, which is semi-permeable. The vacuole contains a more diluted solution than the sugar solution…