Some solutes move freely across cell membranes, while other solutes require
assistance from special gates. Passive transport and active transport are methods of
moving solutes across cell membranes.
Which of the following accurately describes the difference between passive transport
and active transport?
A Passive transport can move molecules both in and out of a cell, but active transport
cannot.
B Passive transport works against a concentration gradient, but active transport does
not.
C Passive transport does not require energy, but active transport does.
D Passive transport requires carrier proteins, but active transport does not.