The overall movement of particles from an area of high concentration to an area of low concentration down a concentration gradient (Occurs both with and without membrane)
Adaptions for Diffusion Exchange in Villi/Alveoli/Gills in fish and Root hair cells
-Large surface area gives increased area for exchange
-Thin membrane gives short diffusion distance
-Good blood supply / ventilation helps to maintain concentration gradient
Surface Area to Volume Ratio
Cutting an object into smaller pieces gives it an overall larger surface area to volume ratio.
Osmosis
The net movement of water from a dilute solution (where there is a high water concentration) to a concentrated solution (where there is a low water concentration) across a partially permeable membrane(which allows the water to move but not solutes like proteins)such as a cell membrane.
Active Transport
Net movement of particles from a low to a high concentration with the use of carrier proteins, and energy from respiration.
