When molecules or atoms move down a concentration gradient across cell membranes, it's called
A) active transport.
B) passive transport.
C) exocytosis.
D) endocytosis.

Question

Quizplus · Accepted Answer

Passive transport is the movement of molecules or atoms across cell membranes from an area of high concentration to an area of low concentration, without requiring energy input. Active transport, on the other hand, moves molecules or atoms against their concentration gradient, requiring energy input. Exocytosis and endocytosis both involve the movement of large molecules or structures into or out of the cell, but they are not related to the movement of molecules down a concentration gradient.

When Molecules or Atoms Move Down a Concentration Gradient Across