Final answer:
Symporters are the primary active transporters for some monosaccharides. They use sodium ions to transport glucose molecules into the cell against their concentration gradient.
Step-by-step explanation:
The primary active transporters for some monosaccharides are symporters. Symporters are secondary active transporters that move two substances in the same direction. The sodium-glucose symporter, for example, uses sodium ions to 'pull' glucose molecules into the cell. The flood of sodium ions through the symporter provides the energy that allows glucose to move through the symporter and into the cell, against its concentration gradient.