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Osmosis is a "type of diffusion where water passes through a semi-permeable membrane from where water is in high concentration to a low concentration

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Information Osmosis is a "type of diffusion where water passes through a semi-permeable membrane from where water is in high concentration to a low concentration." A French scientist (Jean-Antoine Nollett) discovered osmosis in 1748. He discovered it by filling a pig's bladder with alcohol. This was then placed in water for several hours. The water had moved into the pig's bladder but very little alcohol had moved out. The pig's bladder was a semi-permeable membrane. The particles in a liquid are constantly moving. When small particles or water molecules meet a semi-permeable membrane they may pass through. But larger particles, like glucose cannot get through the membrane at all. If there is a high concentration of water molecules on one side of the membrane, then water molecules will pass through the membrane and the water appears to have moved through the membrane to the lower concentration. ...read more.


This is called "Hydrostatic pressure" it works against osmosis. But when plants are faced with a low concentrated water solution (sucrose) the will lose water and become flaccid. Which is the opposite of turgid. So the plant cell will shrink instead of grow. When a plant is placed in an equal concentration solution between water and sugar then the plant will be "in between being turgid or flaccid" so the plant won't shrink but neither will it be able to raise it's leaves in the sunlight. So the plants favour a high concentration of water. Animal cells don't have cell walls so when placed in a pure water solution they may well swell up and burst because there is nothing to support the cell membrane. ...read more.


The level on the higher concentrated side of the membrane will rise whilst the level on the less concentrated side will fall. When the concentration of water is the same on both sides, the movement of water will stay the same in both directions. So now the system is equal. The concentrations of sugar solution depend on the amount of water present. The more distilled water present, the less sugar solution present. The Sucrose has a low concentration of water. So when water is added it will diffuse into the sucrose, diluting it. If more Sucrose is in the container then the diffusion won't happen as much. With 10 millilitres of sucrose and 0 millilitres of pure water it is "a region of low concentration of water." This is because there is much less water. The solution is pure Sucrose because there is no water present to dilute it. ...read more.

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