Practice Electron Transport Chain in a free interactive biochemistry quiz for students in biology, medicine, nursing, and pharmacy. Identify each stage using three choices and receive detailed explanations after checking your answers.
Interactive Electron Transport Chain Quiz
Follow the continuous pathway from top to bottom. The cards use text-based biochemical concept cards, rather than misleading structural-formula images. Each question has exactly one correct option. The article describes the exact scope below: some named stages summarize several reactions, and branches may be represented as conceptual learning checkpoints.
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Reaction and Enzyme Reference Table
| Stage | Enzyme or process | Reaction or key event |
|---|---|---|
| 1 | Complex I | NADH transfers two electrons to the ubiquinone pool; protons are pumped. |
| 2 | Complex III | Q cycle transfers electrons from ubiquinol to cytochrome c; protons are translocated. |
| 3 | Cytochrome c → Complex IV | Cytochrome c delivers electrons to cytochrome c oxidase, Complex IV. |
| 4 | Complex IV | O₂ is the terminal electron acceptor; electrons and protons form H₂O. |
What This Quiz Covers
FADH₂-linked electrons enter via Complex II and other Q-reducing enzymes. Complex II does not pump protons.
Complexes I, III and IV pump protons; ATP synthase is not a component of the four electron-transfer complexes.
Metabolite structures can differ in protonation state, stereochemical depiction, and the presence of carrier groups. Molecular images are intended as biochemical learning aids, not as a complete specification of physiological ionic microstates.
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