LifeLine

The net movement of water molecules across a semipermeable membrane from a region of low solute concentration to a region of higher solute concentration. Because solutes cannot cross a cell membrane unaided, water will move to equalize the two solutions. 

Hypertonic

High solute concentration outside the cell. The water will leave the cell and shrink/ shrivel (undergoes plasmolysis in plants). Higher solute concentration out the cell. Water will leave the cell and shrink. Cytoplasm shrinks from the cell wall. The cells becomes flacid. 

Isotonic

Same solute/solvent concentration. There is no change in the movement. There is an equilibrium state as the solute concentration is same on both sides. 

Hypotonic

High solute concentration inside the cell and can lead to burst of cell. The water will enter the cell and swell (makes the plant rigid). Turgor pressure, the outwards pressure on the plant cell wall due to a large full water vacuole. Lysis, the bursting of cell membrane due to osmotic movement of water into the cell when the cell is in a hypotonic environment. 

Net movement of water across semi-permeable membrane and always takes place in water and membrane. Movement from a dilute solution, so high concentration of water molecules down the concentration gradient to a more concentrated solution so low concentration of water molecules. The water molecules move across a partially permeable membrane. Water molecules move at random so some do go back across the membrane but overall the net effect is that there is movement to the more concentration side or the side with less water until equilibrium is reached or until there is no net movement of water anymore. 

Animal cells shrivel up and in plant cells the membrane and cytoplasm shrink away from the cell wall causing the cell to become flaccid. If osmosis causes lots of movement of water into the cell, plant cells swell and become turgid, they have a strong cell wall which prevents them from bursting. Whereas animal cells don’t have a cell wall and so they burst.