lake Transports in living cells?

Diffusion is the movement of substances down their concentration gradient, or in other words, from an area of higher concentration to lower concentration. Osmosis is diffusion across a membrane, and facilitated diffusion is the movement of substances across a membrane with the help of channel proteins or something similar. The substance still moves down the concentration gradient, but it can't p directly through the membrane and must be "facilitated" by the protein. Active transport, unlike the other three types of transport/movement, requires an energy expenditure by a cell. It also transports substances across a membrane, but requires energy because it moves substances AGAINST their concentration gradient.there