In the Flowchart Below Summarizing Membrane Transport, Both Active and Facilitated

Multiple Choice

In the flowchart below summarizing membrane transport, both active and facilitated transports terminate at separate carrier proteins; explain why the lines do not converge at the same carrier protein.

A) The two processes move items across the membrane in opposite directions; the carriers are positioned on opposite sides of the membrane.
B) During facilitated transport hydrophobic molecules cross the membrane; hydrophilic molecules require active transport to cross the membrane.
C) Energy is required to drive an active transport carrier protein, whereas a facilitated carrier operates down the concentration gradient and requires no energy input.
D) Active transporters move only ions with net charge, whereas facilitated transporters move only polar or neutral molecules.