Describe the different types of membrane transport and how they relate to concentration gradients and energy.

Two main types of active transport are:

Passive transport: The membrane transport that do not require the expense of energy for the transportation of molecules. The molecules are transported along the concentration gradient across the membrane. Passive transport includes osmosis, simple diffusion and facilitated diffusion.

Active transport: The membrane transport that requires the expense of energy in the form of ATP for the transportation of molecules. The molecules are transported against the concentration gradient across the membrane. Active transport includes direct or primary active transport and secondary active transport.