How do unicellular organisms living in water control the entry/exit of water from their cells? are they able to live in any environment? how could this be tested?

Water normally diffuses all through cells relying upon the convergence of solutes in both the cell and the outside condition. osmosis occurs from where the solute fixation is least to where the solute focus is most elevated or all the more sensibly, water goes to weaken the solute; so envision if a cell with a ton of gunk in it swims into unadulterated water, water will begin to move into the cell.