Apentix/AP Biology/Unit 3: Cellular Energetics/Question
AP Biologyeasymcq1 pt

In oxidative phosphorylation, what provides the immediate energy that ATP synthase uses to phosphorylate ADP?

A.Direct oxidation of glucose inside the matrix by ATP synthase
B.Hydrolysis of other ATP molecules already present in the matrix
C.Protons flowing down their electrochemical gradient through ATP synthase
D.Electrons jumping directly from NADH onto ATP synthase

Explanation

Core Concept

The electron transport chain pumps protons from the matrix into the intermembrane space, storing free energy as an electrochemical gradient. When protons diffuse back through ATP synthase, that gradient powers rotation of the enzyme and drives ADP phosphorylation. This coupling of electron transport to proton flow is called chemiosmosis.

Correct Answer

CProtons flowing down their electrochemical gradient through ATP synthase

More Unit 3: Cellular Energetics practice questions

Try a random question →

Practice more AP Biology questions with full explanations

Practice Unit 3: Cellular Energetics Questions →