Answer:
active
hydrophilic
Transporters
Step-by-step explanation:
A molecule moves down its concentration gradient by passive transport, but requires active transport to move up its concentration gradient. - Transporter proteins and ion channels function in membrane transport by providing a hydrophilic pathway through the membrane for specific polar solutes or inorganic ions. - Transporters are highly selective in the solutes they transport, binding the solute at a specific site and changing conformation so as to transport the solute across the membrane.