ETS & Oxidative Phosphorylation — NEET Biology MCQs with Solutions
Free NEET Biology ETS & Oxidative Phosphorylation MCQs with step-by-step solutions (6 questions). Part of Respiration in Plants. Practise online on Prepizo — no login needed.
▶ Practise ETS & Oxidative Phosphorylation online (free)
Questions with solutions
Q1 — ETS & Oxidative Phosphorylation · easy · theory
The electron transport system (ETS) is located in the:
A. Cytoplasm
B. Matrix
C. Outer membrane
D. Inner mitochondrial membrane ✓ Correct
Solution: The ETS complexes and ATP synthase are embedded in the inner mitochondrial membrane (cristae).
Q2 — ETS & Oxidative Phosphorylation · easy · theory
The final electron acceptor of the ETS in aerobic respiration is:
A. Carbon dioxide
B. Oxygen ✓ Correct
C. FAD
D. NAD⁺
Solution: O₂ accepts electrons and combines with protons to form water — the terminal acceptor.
Q3 — ETS & Oxidative Phosphorylation · medium · theory
The oxidation of one NADH via the ETS yields approximately ______ ATP, and one FADH₂ yields ______ ATP:
A. 3 ATP; 2 ATP ✓ Correct
B. 1 ATP; 1 ATP
C. 4 ATP; 3 ATP
D. 2 ATP; 3 ATP
Solution: Each NADH gives ~3 ATP and each FADH₂ ~2 ATP (FADH₂ enters at complex II, bypassing complex I).
Q4 — ETS & Oxidative Phosphorylation · medium · theory
ATP synthesis in the ETS is coupled to a proton gradient across the inner membrane, a mechanism called:
A. Fermentation
B. Oxidative phosphorylation (chemiosmosis) ✓ Correct
C. Photophosphorylation
D. Substrate-level phosphorylation
Solution: Electron flow pumps protons to the intermembrane space; their return through ATP synthase (F0–F1) drives ATP synthesis.
Q5 — ETS & Oxidative Phosphorylation · hard · theory
The theoretical net ATP yield from the complete aerobic oxidation of one glucose molecule is:
A. 2 ATP
B. 4 ATP
C. 38 ATP ✓ Correct
D. 12 ATP
Solution: Glycolysis (2) + Krebs GTP (2) + 10 NADH (30) + 2 FADH₂ (4) = 38 ATP (idealised; actual ~30–32).
Q6 — ETS & Oxidative Phosphorylation · hard · theory
Cytochrome c oxidase (Complex IV) transfers electrons to O₂. If this complex is blocked (e.g. by cyanide), the immediate effect is:
A. Krebs cycle speeds up
B. More ATP is made
C. Glycolysis stops
D. ETS halts, proton gradient collapses and ATP synthesis stops ✓ Correct
Solution: Blocking the terminal oxidase stops electron flow to O₂, collapsing the gradient and halting oxidative phosphorylation.