Osmosis is the scientific process of transferring fluid between molecules. When molecules move in and out of a cell to achieve the same concentration of something, like salt, on both sides, then osmosis is happening. ... The fluid might go back and forth a few times until both solutions are equally concentrated.
The stem relies on the pressure of the plant cells to maintain its rigidity. The plant cells shrink when they lose water, losing their rigidness in the process.
