Respiration in Plants — 5 Must-Know Facts — Summary

Glycolysis → Cytoplasm | 2 ATP + 2 NADH | No $O_{2}$ | Rate-limiting enzyme = PFK — Common to all organisms; fermentation branches here under anaerobic conditions yielding only 2 ATP total.
TCA Cycle → Mitochondrial matrix | 6 NADH + 2 $FADH_{2}$ + 2 GTP + 4 C $O_{2}$ per glucose | Amphibolic — 8 steps; acetyl CoA condenses with OAA to form citrate; OAA is regenerated every turn.
ETS → Inner mitochondrial membrane | NADH = 3 ATP (Complex I) | $FADH_{2}$ = 2 ATP (Complex II) | $O_{2}$ = final $e^{-}$ acceptor at Complex IV → $H_{2}O$ — Chemiosmosis (Peter Mitchell) drives ATP synthase; protons pumped by Complexes I, III, IV.
Total ATP = 38 per glucose (36 with glycerol-3-P shuttle) | 2 direct + 10 NADH × 3 + 2 $FADH_{2}$ × 2 + 2 GTP = 38; fermentation yields only 2 ATP.
RQ values: Carbohydrates = 1.0 | Fats ≈ 0.7 | Proteins ≈ 0.8 | Organic acids ≈ 1.33 | CAM plants (night) = ∞ — RQ = C $O_{2}$ evolved / $O_{2}$ consumed; used to identify respiratory substrate.