Active transport is a type of transport that requires energy to move substances across a membrane. It occurs against a concentration gradient.
The use of energy to move waste materials out of a cell is an EXAMPLE of transport active.
Active transport occurs against a concentration gradient, whereas passive transport (i.e., diffusion) occurs in favor of a concentration gradient.
Active transport can be mediated by membrane proteins that move substances from an area of high concentration to an area of low concentration.
This movement (active transport ) usually requires the energy provided by the hydrolysis of ATP.
Water molecules move across cellular membranes through membrane protein channels called aquaporins that act in favor of a concentration gradient (passive transport).
