Final answer:
In secondary active transport, the transfer of the solute across the membrane is coupled with the electrochemical gradient established by primary active transport. This allows substances like amino acids and glucose to be brought into the cell through membrane channels.
Step-by-step explanation:
In secondary active transport, the transfer of the solute across the membrane is always coupled with the electrochemical gradient established by primary active transport. This means that the movement of the solute is driven by the movement of another solute down its concentration gradient. For example, as sodium ions move into the cell down their concentration gradient, they can pull other substances, like amino acids and glucose, into the cell through membrane channels.