Hydrophobic molecules and small molecules can pass through a membrane
The dye diffuses down a concentration gradient from where it is more
concentrated to where it is less concentrated.
Eventually the solution reaches a dynamic equilibrium: the solute
molecules continue to cross the membrane, but at equal rates in both
Osmotic effect on plant cell.
In a hypotonic environment, where the uptake of water is balanced by
the cell wall pushing back, plant cells are turgid (firm) and are
healthiest. In isotonic environments plant cells become flaccid
(limp). in hypertonic environments the cell membrane pulls away from
the wall and the cell is plasmolyzed.