Cell Biology

A cell takes up glucose through a membrane protein. Glucose moves from a region of higher concentration outside the cell to a region of lower concentration inside, and the process does not directly use ATP. Which mechanism is responsible?

Facilitated diffusion is the correct answer because glucose is polar and does not readily cross the hydrophobic bilayer unaided, but it can move down its concentration gradient through a carrier or channel without direct ATP use. The strongest distractor is primary active transport: that mechanism uses ATP to move a substance against its gradient, which is not described here.