Diffusion and Osmosis: Key Concepts and Examples

Diffusion

Diffusion is the movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached.

Type of transport for diffusion

Passive transport (does not require energy).

Factors affecting the rate of diffusion

Temperature, concentration gradient, surface area, particle size, and the presence of barriers (e.g., membranes).

Example of diffusion in the body

Oxygen diffusing from the alveoli into the bloodstream in the lungs.

Osmosis

Osmosis is the movement of water molecules across a selectively permeable membrane from a region of higher water potential to a region of lower water potential.

Type of transport for osmosis

Passive transport (does not require energy).

Selectively permeable membrane

A membrane that allows certain molecules (like water) to pass through while blocking others.

Effect on animal cell in hypotonic solution

Water enters the cell, causing it to swell and possibly burst (lysis).

Effect on plant cell in hypotonic solution

Water enters the cell, making it turgid (firm) due to pressure against the cell wall.

Effect on cell in hypertonic solution

Water leaves the cell, causing it to shrink (crenation in animal cells, plasmolysis in plant cells).

Isotonic solution

A solution where water moves in and out of the cell at equal rates, so the cell stays the same size.