Introduction to Osmosis and Diffusion

This page delves deeper into the mechanisms of osmosis and diffusion, explaining their differences and the role of cell membranes.

Definition: A selectively permeable cell membrane allows certain materials to pass through while keeping others out.

The page explains that water constantly passes through the cell membrane, and when the movement of water molecules in and out of a cell occurs at the same rate, a state of equilibrium is reached.

Vocabulary:

• Osmosis: The movement of water molecules from an area of high concentration to low concentration. Only the solvent (water) moves.
• Diffusion: The movement of molecules from high concentration to low concentration. Both solvent and solute move.

Example: A diagram illustrates the process of osmosis, showing water molecules moving through a semipermeable membrane from an area of low solute concentration to high solute concentration.

Highlight: The key difference between osmosis and diffusion is that in osmosis, only the solvent (water) moves, while in diffusion, both solvent and solute molecules move.

The page concludes with a visual representation of diffusion, showing how molecules eventually become evenly distributed across a membrane.