Answer
Both primary and secondary transport are active processes that use energy. In the case of primary active transport, the energy for the process is derived directly from the hydrolysis of ATP in a process facilitated by Na+/K+ATPase.
The energy used in secondary active transport is also derived from ATP hydrolysis, but not directly. The steep concentration gradients set up for ions like Na+ and K+ make it easy for these ions to flow down their concentration gradients if given a chance, in the case of Na+, to leak back into the cytosol. These leaks are facilitated by certain membrane transporter proteins that provide channels for ions to flow (leak) down their concentration gradients. When the Na+ ions flow back into cell the potential energy(PE)of the concentration gradient is converted into kinetic energy (KE)of movement or flow, and it is this energy that directly powers secondary active transport.
Work Step by Step
It should always be remembered that the energy for both primary active transport, and secondary active are in the final analysis derived from ATP, the energy currency of mammalian cells.
