Electron transport system and oxidative phosphorylation — practice questions

Question 1 · difficulty L1 · recall

Where is the electron transport system of aerobic respiration located in mitochondria?

• A. Intermembrane space only
• B. Matrix only
• C. Outer mitochondrial membrane
• D. Inner mitochondrial membrane

Question 2 · difficulty L2 · understanding

The complex II of mitochondrial electron transport chain is also known as

• A. Cytochrome c oxidase
• B. NADH dehydrogenase
• C. Cytochrome $\mathrm{bc}_1$
• D. Succinate dehydrogenase

Question 3 · difficulty L2 · understanding

What is the final electron acceptor in the aerobic electron transport chain?

• A. Oxygen
• B. Carbon dioxide
• C. Pyruvate
• D. NAD+

Question 4 · difficulty L3 · understanding

$$\text { Match List-I with List-II: }$$ $$\text { List-I (Process) }$$ $$\text { List-II (Location) }$$ A. Glycolysis I. Inner mitochondrial membrane B. ETS II. Mitochondrial matrix C. Accumulation of protons III. Cytoplasm D. Krebs' cycle IV. Intermembrane space Choose the correct answer from the options given below:

• A. A-IV, B-II, C-I, D-III
• B. A-II, B-III, C-IV, D-I
• C. A-III, B-I, C-IV, D-II
• D. A-I, B-IV, C-III, D-II

Question 5 · difficulty L3 · understanding

Match List-I with List-II: List - I List - II (A) ETS Complex I (I) NADH Dehydrogenase (B) ETS Complex II (II) Cytochrome bC$$_1$$ (C) ETS Complex III (III) Cytochrome C oxidase (D) ETS Complex IV (IV) Succinate Dehydrogenase Choose the correct answer from the options given below :

• A. A-IV, B-I, C-III, D-II
• B. A-I, B-IV, C-II, D-III
• C. A-III, B-I, C-IV, D-II
• D. A-I, B-II, C-IV, D-III

Question 6 · difficulty L3 · understanding

Match List I with List II List - I List - II A. Citric acid cycle I. Cytoplasm B. Glycolysis II. Mitochondrial matrix C. Electron transport system III. Intermembrane space of mitochondria D. Proton gradient IV. Inner mitochondrial membrane Choose the correct answer from the options given below:

• A. A-I, B-II, C-III, D-IV
• B. A-II, B-I, C-IV, D-III
• C. A-III, B-IV, C-I, D-II
• D. A-IV, B-III, C-II, D-I

Question 7 · difficulty L3 · understanding

Which of the following combinations is required for chemiosmosis?

• A. Membrane, proton pump, proton gradient, NADP synthase
• B. Proton pump, electron gradient, ATP synthase
• C. Proton pump, electron gradient, NADP synthase
• D. Membrane, proton pump, proton gradient, ATP synthase

Question 8 · difficulty L3 · understanding

Which of the following statements is incorrect?

• A. Oxidation-reduction reactions produce proton gradient in respiration
• B. During aerobic respiration, role of oxygen is limited to the terminal stage.
• C. In ETC (Electron Transport Chain), one molecule of NADH + H + gives rise to 2 ATP molecules, and one FADH 2 gives rise to 3 ATP molecules
• D. ATP is synthesized through complex V

Question 9 · difficulty L3 · application

An inhibitor blocks ATP synthase but leaves the respiratory electron carriers initially functional. Which process is most directly prevented?

• A. Transfer of electrons from NADH into the chain
• B. Use of the proton gradient to phosphorylate ADP
• C. Formation of pyruvate by glycolysis
• D. Conversion of pyruvate to acetyl-CoA

Question 10 · difficulty L3 · application

A mitochondrial inner membrane becomes freely permeable to protons while electron transfer remains possible. What is the most likely effect on oxidative phosphorylation?

• A. NADH production by glycolysis stops immediately
• B. ATP synthesis rises because protons cross faster
• C. Oxygen is no longer needed as an electron acceptor
• D. ATP synthesis falls because the proton gradient collapses