The net (overall) movement of molecules from a region of higher concentration to a region of lower concentration down a concentration gradient
Concentration gradient
The difference in concentration between a region of higher concentration of a substance and a region of lower concentration of the substance
When the concentration gradient is steeper
The rate of diffusion will be faster
When a concentration gradient exists, diffusion will take place until the particles are evenly distributed throughout the region
Diffusion in biological systems
Important mode of nutrient uptake and gaseous exchange in cells
Cell surface membrane is a partially permeable membrane that allows gases such as oxygen and carbon dioxide to pass through freely but not some other substances
