Final answer:
Substances are moved against a concentration gradient in active transport using energy from ATP, which powers transport mechanisms such as pumps to maintain necessary substance concentrations within the cell.
Step-by-step explanation:
To move substances against a concentration or electrochemical gradient during active transport, a cell must utilize energy, primarily in the form of adenosine triphosphate (ATP).
These active transport mechanisms, often called pumps, expend energy to transport substances like ions and larger molecules across the cell membrane, which is crucial for maintaining the necessary concentrations of such substances within the cell despite passive movements.
The functioning of these active transport processes is heavily reliant on the cell’s metabolic energy and thus is sensitive to substances that may disrupt ATP production.