In biology, a hypotonic solution is a solution that has a lower concentration of solute compared to another solution, typically a cell.
To understand this better, consider these points:
- Solutions consist of a solute and a solvent. The solute is the substance that is dissolved (like salt), and the solvent is the substance doing the dissolving (like water).
- Concentration matters. A hypotonic solution has a lower amount of solute relative to the cell's interior.
- Water movement. When a cell is placed in a hypotonic solution, water will move into the cell because there is a higher concentration of water (and lower concentration of solute) outside the cell than inside.
This influx of water can cause the cell to swell. In animal cells, which lack a cell wall, this can even lead to the cell bursting (lysing). Plant cells, however, have a cell wall that prevents them from bursting. Instead, the cell becomes turgid, which is normal and helps the plant maintain its rigidity.
In summary, hypotonicity describes a solution's lower solute concentration relative to another solution, especially concerning how it affects cells and their osmotic balance.
