* Osmosis is the movement of water across a semi-permeable membrane from a region of high water concentration to a region of low water concentration.
* Solute concentration affects water concentration. The more solutes (like salts, sugars, proteins) dissolved in a solution, the lower the concentration of free water molecules.
* Cells are surrounded by a semi-permeable membrane that allows water to pass through but not many solutes.
Here's how it works:
1. Imagine two compartments separated by a semi-permeable membrane. One compartment has a high concentration of solutes (low water concentration), and the other has a low concentration of solutes (high water concentration).
2. Water molecules will move from the compartment with a higher water concentration (lower solute concentration) to the compartment with a lower water concentration (higher solute concentration).
3. This movement continues until the concentration of water is equal on both sides of the membrane.
In the context of a cell:
* If the environment outside the cell has a higher solute concentration (lower water concentration) than the inside of the cell, water will flow out of the cell by osmosis. This is called hypertonic.
* If the environment outside the cell has a lower solute concentration (higher water concentration) than the inside of the cell, water will flow into the cell by osmosis. This is called hypotonic.
* When the solute concentration is equal inside and outside the cell, there is no net movement of water. This is called isotonic.
In short, water flows into a cell due to the difference in solute concentration between the inside and outside of the cell, not the water concentration itself.
