Osmosis occurs in plants to keep them from wilting. Plant cells have rigid but fully permeable cell walls, and osmosis creates enough pressure against the cell wall to keep the cell turgid. Thus, plant cells can absorb water via osmosis without danger of bursting. Because plants do not have a skeletal system, the pressure created by osmosis is the only way the plant can maintain structure.
When water leaves the permeable membrane of a plant cell, the cell becomes plasmolysed. The organelles and other materials in the cell peel away from the cell wall, and the plant becomes limp. Because plant cells are closely packed together, water will easily transition from cells that have a high concentration of water molecules to those that are depleted of water.
The process of osmosis is important in the preservation of vegetables and fruits. Since water molecules will travel from weak to strong solutions, water can be eliminated from food by placing it in a strong brine or syrup solution. Because bacteria, like plants, have a rigid cell wall, the lack of moisture will cause bacteria that come into contact with the food during the preserving process to die. They are single-celled organisms, so no water from a neighboring cell can transfer into a plasmolysed bacterium as it can in plants.