Flexi Says: Osmosis is the diffusion of water molecules across a selectively permeable membrane from an area of higher concentration to an area of lower concentration. Water moves into and out of cells by osmosis. If a cell is in a hypertonic solution, the solution has a lower water concentration than the cell cytosol, and water moves out of the cell until both solutions are isotonic. Cells placed in a hypotonic solution will take in water across their membrane until both the external solution and the cytosol are isotonic. Fish cells, like all cells, have semi-permeable membranes. Freshwater fish when placed in ocean, is placed in a hypertonic solution, there will be loss of water from its cells. Cells will shrivel and might ultimately die.
