Photosynthesis – Light Reactions & Calvin Cycle
Light Reactions (Thylakoid Membrane):
● Goal: Make ATP & NADPH
● Needs sunlight + water
● Steps:
1. Light hits PSII → electrons excited → ETC
2. Water splits → O₂ released, H⁺ stays → drives ATP
3. Electrons reach PSI → NADP⁺ → NADPH
4. H⁺ gradient → ATP synthase → ATP
FRQ Tip: Oxygen comes from water, not CO₂.
Calvin Cycle (Stroma):
● Goal: Make glucose
● Steps: Fix → Reduce → Regenerate
1. CO₂ + RuBP → 3-PGA
2. ATP + NADPH → G3P (sugar)
3. Some G3P → glucose, some → regenerate RuBP
Mnemonic: “Fix, Reduce, Regenerate = FRR = Funny Rabbits Run” 🐇 (easy to
remember before exams)
2️⃣ Cellular Respiration – Glycolysis, Krebs, ETC
Glycolysis (Cytoplasm):
Light Reactions (Thylakoid Membrane):
● Goal: Make ATP & NADPH
● Needs sunlight + water
● Steps:
1. Light hits PSII → electrons excited → ETC
2. Water splits → O₂ released, H⁺ stays → drives ATP
3. Electrons reach PSI → NADP⁺ → NADPH
4. H⁺ gradient → ATP synthase → ATP
FRQ Tip: Oxygen comes from water, not CO₂.
Calvin Cycle (Stroma):
● Goal: Make glucose
● Steps: Fix → Reduce → Regenerate
1. CO₂ + RuBP → 3-PGA
2. ATP + NADPH → G3P (sugar)
3. Some G3P → glucose, some → regenerate RuBP
Mnemonic: “Fix, Reduce, Regenerate = FRR = Funny Rabbits Run” 🐇 (easy to
remember before exams)
2️⃣ Cellular Respiration – Glycolysis, Krebs, ETC
Glycolysis (Cytoplasm):
