Cell Membrane and Transport Practice Test

Osmosis governs how water moves based on solute concentrations on each side of the membrane. Pure water has essentially no solutes, so its solute concentration is much lower than that inside a typical cell. Water therefore moves into the cell to balance the concentrations, causing the cell to swell. This environment is described as hypotonic because the outside is less concentrated in solutes than the cell’s interior. If you compare other terms, isotonic would mean equal concentrations, so there’s no net water movement; hypertonic would mean more solutes outside, pulling water out and shrinking the cell. Atonic isn’t a standard term for tonicity. In practice, a cell in a hypotonic environment tends to swell, and animal cells can lyse if the influx is extreme, while plant cells become turgid but are less prone to bursting due to their cell wall.