Osmosis is the passive movement of water molecules (H2O) from and area of high concentration, to an area of Low concentration, through a semi-permeable membrane.
We can say, the movement of water molecules from a high concentration of water to a low concentration of water molecules.
Or
We can say, the movement of water from a less concentrated solution (more diluted = more water) to a more concentrated solution (less diluted = less water).
As you can see from the animation above, the level on the more concentrated side of the membrane rises, while the less concentrated falls.
When the concentration is the same on both sides of the membrane the net movement is zero.
For every one going to side A, there is one going to side B.
In plants this is extremely important.
When referring to a plant cell, if the concentration of water is great outside (hypotonic) solution, then the plant cell will absorb the surrounding water. This make the plant cell, Turgid.
If the concentration of water is relatively equal inside and outside of the cell (isotonic). The cell is said to be Flaccid. The plant will ideally want to be Turgid.
If the concentration of water is much higher in the plant cell, compared to its environment (hypertonic) the cell will be plasmolysed.
In animal cells its slightly different. Since the don’t have a cell wall, they are prone to bursting/Lysing.
Crenation - shrinking an animal cell by osmosis
Lysis - bursting an animal cell by osmosis
1. Osmosis is the NET movement of water molecules from a weak solution to a stronger solution across a semi permeable membrane.The water moves down a concentration gradient.
2. Osmosis is the NET movement of water molecules from an area of high water concentration to an area of lower water concentration across a partially-permeable membrane. The water moves down a concentration gradient.
