1. What is the primary function of the electron transport chain (ETC) in cellular respiration?
A) To produce oxygen
B) To generate ATP through oxidative phosphorylation
C) To break down glucose
D) To synthesize carbohydrates
Answer: B) To generate ATP through oxidative phosphorylation
2. Where does the electron transport chain occur in eukaryotic cells?
A) Cytoplasm
B) Mitochondrial matrix
C) Inner mitochondrial membrane
D) Nucleus
Answer: C) Inner mitochondrial membrane
3. What is the final electron acceptor in the electron transport chain?
A) NADH
B) Oxygen
C) FADH2
D) Glucose
Answer: B) Oxygen
4. Which molecule is reduced by the electron transport chain during cellular respiration?
A) Oxygen
B) NADH
C) ATP
D) FADH2
Answer: A) Oxygen
5. Which of the following molecules is produced by the electron transport chain?
A) NADH
B) Water
C) Pyruvate
D) Glucose
Answer: B) Water
6. How many ATP molecules are produced by the electron transport chain for each molecule of glucose?
A) 1
B) 2
C) 32
D) 38
Answer: C) 32
7. What is the role of the proton gradient in the electron transport chain?
A) To produce glucose
B) To generate ATP
C) To release energy as heat
D) To produce oxygen
Answer: B) To generate ATP
8. Which enzyme is responsible for ATP synthesis in the electron transport chain?
A) ATP synthase
B) Cytochrome c
C) NADH dehydrogenase
D) Hexokinase
Answer: A) ATP synthase
9. What is the energy source for ATP production in the electron transport chain?
A) Light energy
B) Glucose
C) Proton gradient
D) Oxygen
Answer: C) Proton gradient
10. Which protein complex transfers electrons from NADH to coenzyme Q in the electron transport chain?
A) Complex I
B) Complex II
C) Complex III
D) Complex IV
Answer: A) Complex I
11. What is the primary role of cytochrome c in the electron transport chain?
A) To produce ATP
B) To transfer electrons between Complex III and Complex IV
C) To generate a proton gradient
D) To reduce oxygen to water
Answer: B) To transfer electrons between Complex III and Complex IV
12. How many molecules of ATP are produced from one NADH molecule in the electron transport chain?
A) 1
B) 2
C) 3
D) 4
Answer: C) 3
13. What is the purpose of oxygen in the electron transport chain?
A) It acts as a proton donor
B) It is the final electron acceptor
C) It produces glucose
D) It generates NADH
Answer: B) It is the final electron acceptor
14. Which of the following complexes in the electron transport chain is responsible for transferring electrons from FADH2?
A) Complex I
B) Complex II
C) Complex III
D) Complex IV
Answer: B) Complex II
15. In which form is energy stored during the electron transport chain?
A) NADH
B) ATP
C) Glucose
D) Heat
Answer: B) ATP
16. How is the proton gradient established during the electron transport chain?
A) By splitting water molecules
B) By pumping protons across the inner mitochondrial membrane
C) By synthesizing glucose
D) By transferring electrons
Answer: B) By pumping protons across the inner mitochondrial membrane
17. Which complex in the electron transport chain directly reduces oxygen to form water?
A) Complex I
B) Complex II
C) Complex III
D) Complex IV
Answer: D) Complex IV
18. What is the result of blocking the electron transport chain with an inhibitor like cyanide?
A) Increased ATP production
B) Decreased proton gradient
C) Oxygen consumption increases
D) Oxygen is consumed faster
Answer: B) Decreased proton gradient
19. In the electron transport chain, which molecule donates electrons to Complex III?
A) NADH
B) FADH2
C) Cytochrome c
D) Coenzyme Q
Answer: D) Coenzyme Q
20. Which of the following statements about the electron transport chain is true?
A) It occurs in the cytoplasm
B) It requires oxygen to function
C) It produces glucose
D) It generates NADH directly
Answer: B) It requires oxygen to function
21. What happens to the energy from the electrons as they pass through the electron transport chain?
A) It is stored in ATP molecules
B) It is used to split glucose
C) It is released as heat
D) It is converted into NADH
Answer: A) It is stored in ATP molecules
22. Which process uses the proton gradient created by the electron transport chain to synthesize ATP?
A) Photosynthesis
B) Substrate-level phosphorylation
C) Chemiosmosis
D) Fermentation
Answer: C) Chemiosmosis
23. What is the role of NADH in the electron transport chain?
A) To serve as the final electron acceptor
B) To donate electrons to the electron transport chain
C) To synthesize ATP
D) To pump protons into the mitochondrial matrix
Answer: B) To donate electrons to the electron transport chain
24. In the electron transport chain, what happens to the energy released from electron transfer?
A) It is used to synthesize glucose
B) It is used to pump protons across the mitochondrial membrane
C) It is converted into NADH
D) It is released as heat
Answer: B) It is used to pump protons across the mitochondrial membrane
25. Which of the following complexes uses energy from electrons to pump protons across the inner mitochondrial membrane?
A) Complex I
B) Complex II
C) Complex III
D) Complex IV
Answer: A) Complex I
26. How is the final electron transport chain product, water, formed?
A) By the combination of electrons and carbon dioxide
B) By the combination of electrons and oxygen
C) By the combination of ATP and oxygen
D) By the splitting of glucose
Answer: B) By the combination of electrons and oxygen
27. What happens when oxygen is absent in the electron transport chain?
A) The electron transport chain continues to function
B) ATP production increases
C) The electron transport chain stops
D) Glucose is metabolized without oxygen
Answer: C) The electron transport chain stops
28. Which of the following compounds is not involved in the electron transport chain?
A) ATP synthase
B) NADH
C) Glucose
D) Cytochrome c
Answer: C) Glucose
29. The process of oxidative phosphorylation involves:
A) The breakdown of glucose
B) The synthesis of glucose
C) ATP production using energy from electron transfer
D) ATP production in the cytoplasm
Answer: C) ATP production using energy from electron transfer
30. What is the primary outcome of the electron transport chain?
A) Glucose is converted into ATP
B) NADH is produced
C) A proton gradient is created
D) Pyruvate is generated
Answer: C) A proton gradient is created
