Describe the mechanism of active transport of substance through cell membrane
Primary active transport moves ions across a membrane and creates a difference in charge across that membrane. The primary active transport system uses ATP to move a substance, such as an ion into the cell, and often at the same time, a second substance is moved out of the cell.
The passive forms of transport, diffusion and osmosis move materials of small molecular weight across membranes. Substances diffuse from areas of high concentration to areas of lower concentration; this process continues until the substance is evenly distributed in a system.