Describes how an external solution affects cell volume: hypotonic causes swelling, hypertonic causes shrinking.
In an isotonic solution there is no net water movement. In hypotonic surroundings water enters: animal cells swell and may lyse, plant cells become turgid. In hypertonic surroundings water leaves: animal cells shrivel (crenation) and plant cells undergo plasmolysis.
This explains why intravenous fluids are made isotonic and why drinking seawater dehydrates you.
Describes how an external solution affects cell volume: hypotonic causes swelling, hypertonic causes shrinking.
Tonicity is one of the 52 topics in Cell Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Vacuole, Cytokinesis, Osmosis.
Paramecium uses a contractile vacuole to survive in a hypotonic pond.
Work through the Beginner topics in Cell Biology first, such as Cell Theory, Prokaryotic Cell, Eukaryotic Cell, then return to Tonicity. Intermediate topics assume the Beginner vocabulary.
The closest topics to Tonicity are Vacuole, Cytokinesis, Osmosis, Cytoplasm. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Tonicity. To practise the whole of Cell Biology, use the Cell Biology quiz.
Tonicity: Describes how an external solution affects cell volume: hypotonic causes swelling, hypertonic causes shrinking. Vacuole: A fluid-filled organelle that stores water and nutrients; very large and central in mature plant cells. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Vacuole and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.
A fluid-filled organelle that stores water and nutrients; very large and central in mature plant cells.
🔬 Cell BiologyDivision of the cytoplasm after nuclear division, by a cleavage furrow in animals or a cell plate in plants.
🔬 Cell BiologyThe diffusion of water across a selectively permeable membrane from lower to higher solute concentration.
🔬 Cell BiologyThe jelly-like fluid and suspended structures between the plasma membrane and nucleus where many reactions occur.
🔬 Cell Biology