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Science14/10/2026

Photosynthesis: Light-Dependent and Light-Independent Reactions: A Visual Explainer

A single labelled flowchart tracing photosynthesis from light capture in the thylakoid membrane through to glucose formation in the stroma.

Photosynthesis: Light-Dependent and Light-Independent Reactions: A Visual Explainer

📌 Revision Pointers

  • Stage 1 (Thylakoid Membrane): PSII → ETC → PSI produces ATP, NADPH and O₂ (from water photolysis)

  • Stage 2 (Stroma/Calvin Cycle): Carbon Fixation (RuBisCO) → Reduction → Regeneration of RuBP, consuming the ATP + NADPH from Stage 1

  • Net result: 6 CO₂ + 18 ATP + 12 NADPH → 1 glucose molecule

One diagram, two stages: how light energy becomes stored chemical energy as glucose.

💭 Conclusion

A frequent UPSC Prelims trap is mixing up the site, enzyme or ATP/NADPH consumption vs. production between the two stages — this diagram fixes that visually.