The form of transport that uses proteins to move other ions and small molecules across the plasma membrane is active transport.

Here's why:

* Active transport requires energy to move substances against their concentration gradient, meaning from an area of low concentration to an area of high concentration.

* Proteins are essential for this process. They act as carriers or pumps, binding to the substance and using energy (often from ATP) to move it across the membrane.

There are two main types of active transport:

1. Primary active transport: Directly uses energy from ATP to move substances. Examples include the sodium-potassium pump and the proton pump.

2. Secondary active transport: Uses the energy stored in an electrochemical gradient created by primary active transport. It couples the movement of one substance down its concentration gradient with the movement of another substance against its concentration gradient.

Passive transport on the other hand, does not require energy and relies on the concentration gradient or electrical gradient to move substances across the membrane. Examples include diffusion, osmosis, and facilitated diffusion.