It is common that we soak raisins in water, and they acquire water by endosmosis. That means that the cells are permeable to water, right? Then why don't they lose water when kept in air? Or kept in sugar without any water?
EDIT: Also, take the example of peeled potatoes. Put them in a hypertonic solution, and they lose water, but when kept there, in air, they don't. How come?