Passive Vs. Active Transport

Passive transport occurs when the concentration of something on one side of membrane is different from the concentration on the other side. It occurs when that substance can pass through the membrane, and always in the direction of more to less. No energy is required to make the substance move. This is like rolling a rock down a hill--it just does it on its own.

Active transport occurs from less to more. It requires energy for transport.
This is like rolling a rock up a hill--you have to push it the entire way!

Active transport requires energy, but passive transport requires none.

Active transport requires a special protein to make the transport occur, but passive transport requires none.

• Both involve the transport of a substance across a membrane, and the change in concentrations on different sides of a membrane. Both are also important to the proper functioning of a cell.