Final answer:
Primary active transport is directly dependent on ATP, as it uses the energy from the hydrolysis of ATP to move substances against their concentration gradients. This establishes an electrochemical gradient that can be used by secondary active transport.
Step-by-step explanation:
Primary active transport is a critical biological process that moves ions or small molecules across a cell membrane, often resulting in a difference in charge across that membrane. This type of active transport is directly dependent on ATP (adenosine triphosphate) because the energy released from the hydrolysis of ATP is what fuels the movement of substances against their concentration gradients. In contrast, secondary active transport uses the electrochemical gradient established by primary active transport to drive the transport of materials. Even though secondary active transport does not directly use ATP, it is still an active process as it relies on the energy stored in the gradients that were created by primary active transport, which did use ATP.