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Calvin Cycle Simulator

Run the Calvin Cycle Simulator MicroSim Fullscreen
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About This MicroSim

This simulator brings the Calvin cycle to life by showing the three major phases (Carbon Fixation, Reduction, RuBP Regeneration) arranged in a circular diagram. As students step through each turn, animated highlights show where CO₂ enters, where ATP/NADPH are consumed, which G3P molecules exit, and how RuBP is regenerated. Running totals keep track of energy inputs and G3P/glucose output, reinforcing why six turns are required to build one glucose molecule.

How to Use

  1. Select Run One Turn to watch a single Calvin cycle turn from start to finish. Observe the highlighted phase, entry arrow, and molecule pool updates.
  2. Use Run 6 Turns (→ 1 glucose) to queue six sequential turns; adjust the speed slider if you want a slower or faster animation.
  3. Hover over any colored arc to read phase-specific details in the right-hand info panel. The totals box at bottom-left updates after each completed turn, showing CO₂ fixed, ATP/NADPH spent, G3P produced, and glucose synthesized.
  4. Click Reset to clear the animation queue and zero all counters so you can run another scenario.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

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<iframe src="https://dmccreary.github.io/biology/sims/calvin-cycle-simulator/main.html"
        height="712px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

11–12 (AP/advanced high-school biology)

Duration

30 minutes (15-minute guided exploration + 15-minute practice/reflection)

Prerequisites

  • Basics of photosynthesis (light reactions vs. Calvin cycle)
  • Familiarity with ATP, NADPH, and carbon fixation terminology
  • Ability to interpret simple energy accounting tables

Activities

  1. Engage (5 min)
  2. Ask: “Why do plants need six CO₂ molecules to make one glucose?”

  3. Show the MicroSim in its default state. Invite students to predict which phase requires the most ATP and which releases product.

  4. Explore (10 min)

  5. Students work in pairs to run one turn at a time, filling out a quick log: CO₂ fixed, ATP used, NADPH used, G3P exiting.
  6. They hover each arc to note the biochemical logic (RuBisCO/CO₂ entry, reduction of 3-PGA, RuBP regeneration).

  7. Encourage them to run all six turns to watch glucose formation and record the totals displayed in the bottom-left panel.

  8. Explain (10 min)

  9. Facilitate a whole-class discussion:
    • What fraction of G3P exits to build sugars?
    • Why does the simulator keep showing ATP usage during RuBP regeneration?
    • Compare the totals for 6 turns (18 ATP, 12 NADPH) with textbook numbers.

  10. Use the info panel to reinforce which energy carriers are consumed in each phase.

  11. Extend (Optional homework or assessment)

  12. Students use the simulator to create a short annotated screenshot or video explaining the fate of carbon atoms through six turns.
  13. Provide hypothetical scenarios (e.g., “What happens if the plant is short on NADPH?”) and have them predict changes using the interactive elements.

Assessment

  • Exit ticket: “After 6 turns, how many G3P molecules have left the cycle, and how many ATP/NADPH were spent? Explain why only one glucose results.”
  • Observation checklist while students run the sim (do they track energy usage, hover to read phase details, and interpret totals?).
  • Optional: short written explanation comparing Carbon Fixation vs. Reduction vs. RuBP Regeneration, referencing specific elements of the simulator.

References

  1. Nelson, D. and Cox, M. Lehninger Principles of Biochemistry, 8th ed. (Calvin cycle chapter).
  2. AP Biology Course and Exam Description (2024) – Unit 3, Photosynthesis.
  3. Taiz & Zeiger. Plant Physiology (Energy transformations in the chloroplast).