| Osmotic Pressure |
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Information AboutOsmotic Pressure |
| CATEGORIES ABOUT OSMOTIC PRESSURE | |
| cell biology | |
| membrane biology | |
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When a Biological Cell is in a Hypotonic environment (the cell interior contains a lower concentration of Water than its exterior), water flows across the Cell Membrane into the cell, causing it to expand. The Membrane (or, in Plant Cell s, the Cell Wall ) restricts the expansion, which causes an increase in pressure. The resulting pressure is called turgor. This pressure is what prevents more water from flowing into the cell, thus creating a pressure equilibrium between water flowing down the Concentration Gradient and the taut membrane pushing back. In this example, the equilibrium prevents the cell from ever becoming Isotonic to its environment. Cells not adapted to hypotonic environments, with the flow of water into them but no strong membrane or cell wall, will burst. The osmotic pressure π of a dilute solution can be calculated using the formula : where M R T Note the similarity of the above formula to the Ideal Gas Law , and also that osmotic pressure is not dependent on particle charge. APPLICATIONS Osmotic pressure is the basis of Reverse Osmosis , a process commonly used to purify water. The water to be purified is placed in a chamber and put under an amount of pressure greater than the osmotic pressure exerted by the water and the solutes dissolved in it. Part of the chamber opens to a differentially permeable membrane that lets water molecules through, but not the solute particles. The osmotic pressure of ocean water is about 27 Atm . Reverse osmosis Desalinator s use pressures around 50 atm to produce fresh water from ocean salt water. Osmotic pressure is necessary for most plants. It is the resulting turgor that allows herbaceous plants to stand upright, and how plants regulate the aperture of their Stomata SEE ALSO EXTERNAL LINKS |
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