How can you explain that plant cell act an osmotic system?

(i) A plant cell has a cell membrane and cell wall as its boundary. The cell wall is freely
permeable to water, hence it is not barrier to movement, while the plasma membrane is selectively permeable.
(ii) In plant cells, the cells usually contains a large central vacuole, whose contents, the vadholar sap, contribute to the solute potential of the cell. The difference between in the concentration of vacuolar sap and external solution results in osmosis.