Oxidative Phosphorylation and Chemiosmosis · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

The Battery and the Motor

Science · Organisms & Life Processes · ages 17-18
Name ______________________   Date ____________

  1. Where is ATP synthase, and what does it do?

    • In the cytosol, breaking down glucose
    • In the outer membrane, pumping electrons
    • In the inner membrane, making ATP as protons flow back

  2. What does the electron transfer chain do with the energy it releases?

    • It pumps protons
    • It burns protons to make heat
    • It splits water to release oxygen

  3. What does oxygen do at the end of the chain?

    • It pumps protons into the space
    • Accepts electrons to form water
    • It splits glucose into pyruvate

  4. Which sentence best describes chemiosmosis?

    • Electrons hopping between carriers in the membrane
    • Oxygen joining electrons to form water
    • Protons flowing through ATP synthase to drive ATP formation

  5. What happens to ATP output when oxygen runs out?

    • It rises as the chain speeds up
    • It stays level while fermentation waits
    • It crashes as the chain backs up and the gradient fails

  6. Each reduced NAD funds roughly two to three ATP. Where is that ATP actually made?

    • Inside the intermembrane fluid
    • At ATP synthase
    • Directly on the chain carriers

  7. Without oxygen, the chain keeps pumping and ATP output falls only slightly. This claim is true.

    Circle one:   True   False

  8. A student says a punctured membrane stops ATP because electrons can no longer move. This claim is true.

    Circle one:   True   False

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Answer key

For grown-ups. Fold this page away before handing over the rest.

The Battery and the Motor W1-mt_1wP3-14Y4V-s1

  1. In the inner membrane, making ATP as protons flow back · ATP synthase sits in the inner membrane and couples returning protons to ATP formation.
  2. It pumps protons · Released electron energy pumps protons into the intermembrane space, storing energy as a gradient.
  3. Accepts electrons to form water · Oxygen is the final acceptor, joining electrons and protons to form water.
  4. Protons flowing through ATP synthase to drive ATP formation · Chemiosmosis is the spending half: gradient flow through ATP synthase makes ATP.
  5. It crashes as the chain backs up and the gradient fails · With no final acceptor the chain jams, the gradient collapses, and chemiosmosis stops.
  6. At ATP synthase · The carriers only build the gradient. ATP synthase spends it to make the ATP.
  7. False · No final acceptor jams the whole chain, so pumping stops and output crashes.
  8. False · Electrons may still flow. ATP stops because the gradient that drives ATP synthase is gone.
Worksheet · LightMySky