PP-02: Respiration in Plants — Exam-Day Cheat Sheet

Stage Locations

ATP Yield (Per Glucose)

• Glycolysis: 2 ATP + 2 NADH
• Link reaction: 2 NADH (→ 6 ATP in ETS)
• TCA cycle: 2 GTP + 6 NADH + 2 $FADH_{2}$ (→ 24 ATP in ETS)
• Total: 38 ATP (or 36 with glycerol-3-P shuttle)
• Formula: 2 + 2 + (10 × 3) + (2 × 2) = 38

Key Yields

• NADH → 3 ATP | $FADH_{2}$ → 2 ATP
• $CO_{2}$ released: 0 (glycolysis) + 2 (link) + 4 (TCA) = 6 total

RQ Values (Must Know All 5)

Fermentation

• Yeast: pyruvate → ethanol + $CO_{2}$ (pyruvate decarboxylase → alcohol dehydrogenase)
• Muscles/Lactobacillus: pyruvate → lactate (lactate dehydrogenase)
• Both: only 2 ATP; purpose = regenerate N$AD^{+}$

ETS Complexes

• Complex I = NADH dehydrogenase (NADH enters; pumps $H^{+}$)
• Complex II = Succinate dehydrogenase ($FADH_{2}$ enters; no $H^{+}$ pump)
• Complex III = Cytochrome bc1 (pumps $H^{+}$)
• Complex IV = Cytochrome c oxidase → $O_{2}$ → $H_{2}O$ (pumps $H^{+}$)
• Mobile carriers: CoQ (between I/II and III); Cyt c (between III and IV)

Key Enzymes

Critical Facts (1-mark answers)

• Chemiosmosis proposed by: Peter Mitchell
• TCA cycle named after: Hans Krebs
• TCA cycle nature: Amphibolic
• Glycolysis occurs in: Cytoplasm (NOT mitochondria)
• Final $e^{-}$ acceptor in ETS: $O_{2}$
• $FADH_{2}$ enters ETS at: Complex II (bypasses CI → 2 ATP only)