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Biologia w szkole średniej
Kurs: Biologia w szkole średniej > Rozdział 3
Lekcja 4: Osmoza i toniczośćOsmosis and tonicity review
Pojęcia kluczowe
| Term | Meaning |
|---|---|
| Passive transport | Type of transport that does not require energy to occur |
| Osmosis | The net movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration |
| Tonicity | The ability of an extracellular solution to make water move into or out of a cell by osmosis |
Osmosis
Osmosis is a passive transport process during which water moves from areas where solutes are less concentrated to areas where they are more concentrated.
Tonicity and cells
| Tonicity of solution | Solute concentration | Water moves... |
|---|---|---|
| Hypertonic | Higher solute in solution than in cell | Out of the cell |
| Isotonic | Equal amounts of solute in cell and solution | Into and out of cell at the same time |
| Hypotonic | Lower solute in solution than in cell | Into the cell |
Często spotykane błędy i nieporozumienia
- In osmosis, water moves from areas of low concentration of solute to areas of high concentration of solute. But wait! Didn’t we say that osmosis is a passive process? It is! Water does still follow its concentration gradient, so it might be easier to think that water moves from where the concentration of water is high to where the concentration of water is low rather than thinking about solute concentration.
- Hypertonic and hypotonic are not the same. If a cell is put into a hypertonic solution, water will leave the cell. A quick tip to remembering this is to visualize “hyper” kids who want to go play outside! In contrast, when a cell is put into a hypotonic solution, water will enter the cell. Another trick to remembering this is that the cell swells and gets round like the “o” in hypo!
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