"active transport." YourDictionary, n.d. Web. 11 October 2018. <http://www.yourdictionary.com/active-transport>.
active transport. (n.d.). Retrieved October 11th, 2018, from http://www.yourdictionary.com/active-transport
The movement of a chemical substance through a gradient of concentration or electrical potential in the direction opposite to normal diffusion, requiring the expenditure of energy: active transport across a cell membrane.