Active transport is characterized by:

Active transport is characterized by the movement of substances against their concentration gradient, which means that molecules are moved from an area of lower concentration to an area of higher concentration. This process requires energy, typically in the form of ATP, because it is moving substances in the opposite direction of what would occur naturally through passive transport, where molecules tend to move from regions of higher concentration to lower concentration.

This active process is crucial for various cellular functions, including nutrient uptake and waste removal, allowing cells to maintain necessary concentrations of ions and other substances. By using energy to move materials against the gradient, cells can regulate their internal environments more effectively, ensuring optimal conditions for cellular processes.