What do the words hypotonic, isotonic , and hypertonic mean?

1 Answer
Mar 10, 2015

These words are used to describe the relative concentrations of dissolved salts in two bodies of water separated by a semi-permeable membrane. For example, a cell can be filled with water while surrounded by water. Therefore, two bodies of water are separated by a membrane.

Hypotonic describes the water that is less salty than the other body of water. Water will flow out through the membrane and towards the salty side.

Isotonic means that both sides of water are equally salty. Water flows through the membrane in both directions.

Hypertonic describes the water that is saltier than the other side. Water will flow towards this side.

Therefore, water will flow out of the hypotonic side and into the hypertonic side until their salt concentrations become equal, which would make them isotonic.

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