Final answer:
The belief that transport against an electrochemical gradient is passive is false; such transport requires energy and is therefore classified as active transport, which employs cellular energy in the form of ATP.
Step-by-step explanation:
If the direction of the net flux of an ion is against its electrochemical gradient, then the statement that this transport is passive is false. Transporting ions or molecules against their concentration or electrochemical gradient requires energy, hence, this process is called active transport. Active transport mechanisms, including carrier proteins or pumps, utilize energy often in the form of ATP. These processes maintain cellular ion concentrations despite passive movements that tend to equalize concentrations inside and outside of the cell.
Passive transport processes, like simple diffusion and facilitated diffusion, do not require cellular energy and occur when substances move down their electrochemical gradient. In contrast, active transport moves ions up their concentration gradient, which is a unidirectional process consuming cellular energy. For example, in a red blood cell, the energy-intensive pumping out of sodium and intake of potassium are clear instances of active transport.