Respiration - glycolysis Krebs cycle electron transport chain oxidative phosphorylation - Question Bank

1. Which enzyme catalyzes the formation of ATP from ADP and Pi using the energy from a proton gradient?
A) Hexokinase
B) Pyruvate kinase
C) ATP synthase
D) Isocitrate dehydrogenase
2. In the overall process of aerobic respiration, the carbon atoms from glucose end up as:
A) Water
B) ATP
C) Carbon dioxide
D) NADH
3. The 'chemiosmotic hypothesis' explains how ATP is synthesized via:
A) The direct transfer of phosphate from substrate to ADP
B) The flow of electrons through membrane proteins
C) The coupling of proton gradient energy to ATP synthase activity
D) The reduction of oxygen
4. Which pathway generates ATP without the involvement of the electron transport chain?
A) Oxidative phosphorylation
B) Krebs cycle
C) Substrate-level phosphorylation
D) Chemiosmosis
5. The inner mitochondrial membrane is impermeable to protons, which is essential for:
A) Facilitating the transport of pyruvate
B) Allowing the buildup of a proton gradient for ATP synthesis
C) Preventing the leakage of electrons
D) Carrying out glycolysis
6. Which of the following is a characteristic of anaerobic respiration compared to aerobic respiration?
A) Higher ATP yield per glucose molecule
B) Involves the electron transport chain with oxygen as the final acceptor
C) Lower ATP yield per glucose molecule
D) Complete oxidation of glucose
7. What is the primary function of the Krebs cycle in the context of cellular respiration?
A) To directly produce a large amount of ATP
B) To oxidize acetyl-CoA, producing NADH, FADH2, and CO2
C) To regenerate glucose from pyruvate
D) To transfer electrons to oxygen
8. The energy released from NADH oxidation in Complex I of the ETC is sufficient to pump how many protons?
A) 4 protons
B) 2 protons
C) 1 proton
D) 0 protons
9. Which of the following intermediates is part of both glycolysis and the Calvin cycle?
A) Glucose-6-phosphate
B) Glyceraldehyde-3-phosphate
C) Pyruvate
D) Acetyl-CoA
10. The complete aerobic respiration of one glucose molecule yields approximately how many ATP molecules?
A) 2-4
B) 10-12
C) 30-32
D) 36-38
11. Substrate-level phosphorylation occurs during which stage(s) of cellular respiration?
A) Glycolysis and Krebs cycle only
B) Krebs cycle and Electron Transport Chain only
C) Glycolysis, Krebs cycle, and Electron Transport Chain
D) Electron Transport Chain only
12. What happens to the oxygen atoms at the end of the electron transport chain?
A) They are released as CO2
B) They accept electrons and protons to form water
C) They are used to synthesize ATP
D) They are converted into NAD+
13. The process of oxidative phosphorylation involves both:
A) Glycolysis and Krebs cycle
B) Electron transport chain and chemiosmosis
C) Fermentation and glycolysis
D) Pyruvate oxidation and substrate-level phosphorylation
14. Which complex in the ETC directly receives electrons from FADH2?
A) Complex I
B) Complex II
C) Complex III
D) Complex IV
15. The conversion of pyruvate to acetyl-CoA is catalyzed by the pyruvate dehydrogenase complex and occurs in the:
A) Cytoplasm
B) Mitochondrial matrix
C) Inner mitochondrial membrane
D) Intermembrane space
16. Which of the following is a key regulatory enzyme in glycolysis?
A) Aldolase
B) Triose phosphate isomerase
C) Phosphofructokinase-1
D) Enolase
17. The net equation for glycolysis shows that glucose is broken down into:
A) 2 Pyruvate + 2 ATP + 2 NADH
B) 2 Pyruvate + 4 ATP + 2 NADH
C) 1 Pyruvate + 2 ATP + 2 NADH
D) 2 Acetyl-CoA + 2 ATP + 2 NADH
18. During the oxidation of one molecule of NADH in the ETC, approximately how many protons are pumped across the inner mitochondrial membrane?
A) 4-6
B) 10-12
C) 2-3
D) 1-2
19. The enzyme ATP synthase is also known as:
A) Complex V
B) Complex IV
C) Succinate dehydrogenase
D) Pyruvate dehydrogenase
20. Which step in respiration involves the conversion of citrate to isocitrate?
A) Glycolysis
B) Pyruvate oxidation
C) Krebs cycle
D) Electron transport chain
21. In prokaryotes, where does the Electron Transport Chain and oxidative phosphorylation occur?
A) Nucleoid region
B) Cytoplasm
C) Plasma membrane
D) Ribosomes
22. What is the primary role of NADH and FADH2 in cellular respiration?
A) To directly provide energy for cellular work
B) To carry electrons to the electron transport chain
C) To act as enzymes in the Krebs cycle
D) To transport glucose into the mitochondria
23. Which of the following statements about the ATP yield from cellular respiration is true?
A) Glycolysis yields more ATP than oxidative phosphorylation.
B) The Krebs cycle directly produces a large amount of ATP.
C) Oxidative phosphorylation generates the majority of ATP.
D) Anaerobic respiration yields more ATP than aerobic respiration.
24. The 'proton motive force' refers to:
A) The flow of electrons
B) The concentration gradient of protons and the electrical potential across the inner mitochondrial membrane
C) The synthesis of ATP
D) The reduction of oxygen
25. Which molecule is responsible for coupling the proton gradient to ATP synthesis in oxidative phosphorylation?
A) Ubiquinone
B) Cytochrome c
C) ATP synthase
D) Oxygen
26. The energy released during the electron transport chain is used to:
A) Reduce NADP+
B) Create a proton gradient
C) Synthesize pyruvate
D) Regenerate FAD
27. Oxidative phosphorylation directly produces:
A) NADH
B) FADH2
C) ATP
D) CO2
28. What is the term for the movement of protons across the inner mitochondrial membrane through ATP synthase?
A) Electron transport
B) Oxidative phosphorylation
C) Chemiosmosis
D) Glycolysis
29. Which complex in the ETC pumps protons from the mitochondrial matrix to the intermembrane space?
A) Complex I
B) Complex II
C) Complex III and IV
D) Complex V
30. The process by which electrons are passed along a series of protein complexes in the ETC is called:
A) Substrate-level phosphorylation
B) Oxidative phosphorylation
C) Photophosphorylation
D) Chemiosmosis
31. What is the final electron acceptor in the Electron Transport Chain?
A) Oxygen
B) Water
C) NADP+
D) ATP
32. Which of the following is NOT a component of the Electron Transport Chain?
A) Ubiquinone
B) Cytochrome c
C) ATP synthase
D) Citrate synthase
33. Where is the Electron Transport Chain located in eukaryotic cells?
A) Cytoplasm
B) Mitochondrial matrix
C) Inner mitochondrial membrane
D) Outer mitochondrial membrane
34. The primary role of the Electron Transport Chain (ETC) is to:
A) Synthesize glucose
B) Generate ATP by oxidizing NADH and FADH2
C) Break down pyruvate
D) Fix carbon dioxide
35. Which electron carrier is produced in the Krebs cycle and subsequently used in the Electron Transport Chain?
A) NAD+
B) FAD
C) ATP
D) ADP
36. The regeneration of oxaloacetate in the Krebs cycle is crucial for:
A) Generating more ATP
B) Continuously accepting acetyl-CoA
C) Producing FADH2
D) Releasing CO2
37. Which enzyme in the Krebs cycle is responsible for the substrate-level phosphorylation of GDP to GTP?
A) Isocitrate dehydrogenase
B) Alpha-ketoglutarate dehydrogenase
C) Succinyl-CoA synthetase
D) Malate dehydrogenase
38. How many molecules of CO2 are released per turn of the Krebs cycle?
A) 1
B) 2
C) 3
D) 4
39. Which of the following is a direct product of the Krebs cycle, besides CO2 and ATP?
A) Pyruvate
B) Lactate
C) NADH and FADH2
D) Glucose
40. The Krebs cycle begins with the condensation of acetyl-CoA with which molecule?
A) Malate
B) Succinate
C) Fumarate
D) Oxaloacetate
41. Where does the Krebs cycle (Citric Acid Cycle) take place in eukaryotic cells?
A) Cytoplasm
B) Mitochondrial matrix
C) Inner mitochondrial membrane
D) Outer mitochondrial membrane
42. Which molecule links glycolysis to the Krebs cycle?
A) Pyruvate
B) Acetyl-CoA
C) Citrate
D) Oxaloacetate
43. In alcoholic fermentation, pyruvate is decarboxylated to form:
A) Ethanol and CO2
B) Lactic acid
C) Acetaldehyde
D) Oxaloacetate
44. Under anaerobic conditions, pyruvate is converted to lactic acid in which process?
A) Alcoholic fermentation
B) Lactic acid fermentation
C) Citric acid cycle
D) Oxidative phosphorylation
45. What are the end products of glycolysis?
A) Acetyl-CoA and CO2
B) Pyruvate, ATP, and NADH
C) Citrate and NADH
D) Glucose-6-phosphate and ATP
46. Which enzyme catalyzes the committed step in glycolysis?
A) Hexokinase
B) Phosphofructokinase-1
C) Pyruvate kinase
D) Aldolase
47. What is the net gain of ATP molecules from one molecule of glucose during glycolysis?
A) 1 ATP
B) 2 ATP
C) 4 ATP
D) 8 ATP
48. In which part of the cell does glycolysis occur?
A) Mitochondrial matrix
B) Cytoplasm
C) Thylakoid membrane
D) Inner mitochondrial membrane
49. Which is the first step in the breakdown of glucose during cellular respiration?
A) Electron Transport Chain
B) Krebs Cycle
C) Glycolysis
D) Oxidative Phosphorylation