What Causes Osmosis and Why does it Occur
Basic Characteristics of Osmosis
Examples of Osmosis
What Factors Affect Osmosis
Different Types Of Osmotic Solutions and Their Effect on Osmosis
What Are The Different Types Of Osmosis
Osmosis was first thoroughly studied in 1877, by German plant physiologist Wilhelm Pfeffer. The general term ‘osmose’ (now osmosis) was introduced in 1854 by British chemist Thomas Graham. In Plants
Roots of plants have a higher solute concentration than the surrounding soil, so water flows into the roots which are absorbed by the plants through osmosis The opening and closing of guard cells, responsible for gas exchange in plants, depends on the absorption of water by osmosis
In Animals
Human body infected with cholera-causing bacteria perform osmosis to reverse the flow of water absorption in the intestine, causing excess water loss, leading to severe dehydration and sometimes death If a freshwater fish is transferred to saltwater or vice versa, the fish will die of too much osmosis, which will disrupt the balance of salts in its body. Cells take up nutrients and minerals into the cell and also get rid of their waste products by osmosis
- Area of Interaction – More the surface area of interacting molecules, higher is the rate of osmosis.
- Concentration Gradient or Osmotic Gradient – Greater the difference in concentration gradient between the regions, higher is the rate of diffusion
- Osmotic Pressure – Higher the hydrostatic pressure exerted by a solution across a semipermeable membrane from a pure solvent, slower is the rate of diffusion a) Isotonic Solutions: Have the same concentration of solutes both inside and outside the cell. Here there is no net movement of solvents across the membrane as the amount entering and leaving out the cell are equal. b) Hypotonic Solutions: Have a higher concentration of solutes inside the cell than outside. When this occurs, more solvent enters the cell compared to the amount that leaves out, to balance the concentration of solute on both sides of the membrane. c) Hypertonic Solutions: Have a higher concentration of solutes outside the cell than inside it. Here more solvent leaves the cell compared to the amount that enters inside the membrane.
Endosmosis
It is the process by which water moves inside the cell when placed in a hypotonic solution causing them to swell up and become rigid. Endosmosis occurs because the solute concentration of the surrounding solution is less compared to the concentration inside the cell.
Exosmosis
It is the process by which water moves out the cell when placed in a hypertonic solution causing them to become flaccid. Exosmosis occurs because the solute concentration of the surrounding solution is higher than inside the cytoplasm. In some extreme cases of exosmosis, the cells lose excess water, and the cell membrane separates from the cell wall, a process known as plasmolysis.
