Answer:
Primary active transport
Explanation:
Primary active transport is the transport in which molecules are moved against their gradient, with direct use of ATP as an energy source. Na/K pump is an example of primary active transport: Na ions are transported out of cell, K ions are moved into the cell. This pumps maintain concentrations of those ions and also creates voltage across the cell membrane, which can be used for the secondary active transport of other molecules (e.g. glucose).
