Osmosis is the diffusion of water particles through a selectively permeable membrane from areas of high water concentration (low solute) to areas of low water concentration (high solute).
From revision notes:
(Water molecules always travel through a cell membrane; this is the selectively permeable membrane. This selectively permeable membrane only allows water through, and does not allow though any solutes.
Water molecules are much smaller than the dissolved particles (solutes) and so are able to pass through the pores in the membrane.
This means that water will still move, either; from PURE WATER (DISTILLED WATER) into a DILUTE SOLUTIONS, or; from a DILUTE SOLUTION into a more CONCENTRATED SOLUTION. The more concentrated a solution is, the less water there is.
We can use this theory of osmosis to explain the movement of water into the root hairs cells of plants. The water in the soil is a dilute solution; the cytoplasm in the root hair is a concentrated solution. Therefore the water tends to move from the soil through the cell membrane of the root hair cells and into the cytoplasm of the root hair cell.
It is essential that cells contain the correct amount of water. Not enough water and cells will collapse, plants wilt and animal cells stop working properly. Too much water and cells swell up and burst.)
From text book:
If the solution surrounding our red blood cells contained less water than the cytoplasm of the red blood cells, water would pass out of the cells faster than it would enter. The cells would then shrink and die. If the opposite occurred and there was more water outside the cells there would be a net gain of water and the cells would burst. Therefore it is vital that the composition of out blood and other body fluids is regulated. This is an example of homeostasis or regulation of our internal environment.
Diffusion is affected by the following factors:
* Concentration – the greater the difference in concentration between...