Tonicity: hypertonic, isotonic & hypotonic solutions (article) | Khan
https://www.khanacademy.org/science/ap-biology/cell-structure-and-function/mechanisms-of-transport-tonicity-and-osmoregulation/a/osmosis
WebTonicity is a concern for all living things, particularly those that lack rigid cell walls and live in hyper- or hypotonic environments. For example, paramecia—pictured below—and amoebas, which are protists that lack cell walls, may have specialized structures called contractile vacuoles.
DA: 32 PA: 44 MOZ Rank: 92