Describe what is meant by active transport and state one way in which it is different to simple diffusion

Active transport is the movement of substances from an area of lower concentration to an area of higher concentration. Movement is going against the concentration gradient. This is ATP requiring.Active transport is different from simple diffusion as active transport requires ATP while simple diffusion does not require ATP. Active transport goes against the concentration gradient while simple diffusion goes down the concentration gradient. Simple diffusion transports small and uncharged molecules, such as O₂, while ATP transports larger or charged molecules such as K+