The cell has several types of membrane transport alternatives, being the simple diffusion, facilitated diffusion, and active transport one of the options for the cell to exchange molecules between internal and external environment.
The types of cell transport:
1 - Simple Diffusion: is a process that does not need energy (passive), used to transport small and nonpolar molecules from a region of higher concentration into a region of lower concentration (in the gradient concentration direction);
2 - Facilitated Diffusion: is a process that does not need energy (passive), used to transport larger ions and polar molecules with the help of carrier proteins or pore proteins (transport proteins);
3 - Active Transport: There is two types of active transport, primary active transport is used for molecules moving against their gradient coupled to the hydrolysis of ATP, and secondary active transport is for molecules going with more molecules against their gradient. It is a process that needs energy (active) to happen, going always against the gradient of concentration of the cell.