Biochem Module 7 Exam Exam () Portage
Learning Questions and Verified Answers, 100%
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Portage CHEM 210 – Module 7: Bioenergetics & Metabolic Pathways
Key Topics You Must Know (from the syllabus):
• Metabolic terminology: flux, regulation, control of pathways.
• Glycolysis steps, enzymes, ATP yield, and regulation.
• Pyruvate fate & link to the citric acid (Krebs) cycle.
• Citric acid cycle reactions, key intermediates, coenzymes & energy carriers.
• Fatty acid β-oxidation — even vs odd chain; acetyl-CoA production.
• ATP production via the electron transport chain and oxidative phosphorylation. (Portage
Learning)
Module 7 – 50 Practice Questions (With Answer -s & Explanations)
Bioenergetics & Thermodynamics
1. True or False: A reaction with a negative ΔG is non-spontaneous.**
Answer -: False
Explanation: A negative ΔG means the reaction is spontaneous under standard conditions.
2.
3. What term describes the rate of flow through a metabolic pathway?
A. Capacity
B. Flux
C. Efficiency
D. Yield
, Answer -: B — Flux
Explanation: Flux describes how rapidly metabolites move through a pathway.
Glycolysis
3. Which enzyme catalyzes the first step of glycolysis (phosphorylation of glucose)?
A. Hexokinase
B. Phosphofructokinase
C. Aldolase
D. Pyruvate kinase
Answer -: A — Hexokinase
Explanation: Hexokinase converts glucose → glucose-6-phosphate using ATP.
4. How many ATP molecules are consumed in the energy-investment stage of glycolysis?
A. 1
B. 2
C. 3
D. 4
Answer -: B — 2
Explanation: Two ATPs are used (hexokinase and phosphofructokinase steps).
5. Which glycolytic step generates ATP via substrate-level phosphorylation?
A. Glucose → G6P
B. F1,6BP → G3P
C. 1,3-BPG → 3-PG
D. NAD+ → NADH
Answer -: C — 1,3-BPG to 3-PG
Explanation: This step directly produces ATP by phosphate transfer to ADP.
Pyruvate & Acetyl-CoA
6. Pyruvate enters the mitochondrion and is converted to acetyl-CoA by:
A. Pyruvate dehydrogenase
B. Lactate dehydrogenase
C. Pyruvate kinase
D. Transketolase
Answer -: A — Pyruvate dehydrogenase
Explanation: This irreversible reaction links glycolysis to the TCA cycle.
Citric Acid (Krebs) Cycle
7. Which molecule combines with acetyl-CoA to begin the citric acid cycle?
A. Oxaloacetate
, B. Citrate
C. Isocitrate
D. Malate
Answer -: A — Oxaloacetate
Explanation: Acetyl-CoA + oxaloacetate → citrate to start the cycle.
8. How many NADH are produced in one turn of the citric acid cycle?
A. 1
B. 2
C. 3
D. 4
Answer -: C — 3
Explanation: NADH from isocitrate DH, α-KG DH, and malate DH.
9. Which step directly produces GTP (or ATP) in the TCA cycle?
A. Isocitrate → α-ketoglutarate
B. Succinyl-CoA → succinate
C. Fumarate → malate
D. Malate → oxaloacetate
Answer -: B — Succinyl-CoA → succinate
Explanation: This step yields GTP via substrate-level phosphorylation.
Fatty Acid Oxidation (β-Oxidation)
10. β-Oxidation occurs in the:
A. Cytosol
B. Mitochondrial matrix
C. Endoplasmic reticulum
D. Nucleus
Answer -: B — Mitochondrial matrix
Explanation: Fatty acids are activated in cytosol then transported into mitochondria for
β-oxidation.
11. Each round of β-oxidation shortens a fatty acid chain by how many carbons?
A. 1
B. 2
C. 3
D. 4
Answer -: B — 2 carbons
Explanation: Each cycle removes an acetyl-CoA unit.
ATP Production & Oxidative Phosphorylation
Learning Questions and Verified Answers, 100%
Guarantee Pass
Portage CHEM 210 – Module 7: Bioenergetics & Metabolic Pathways
Key Topics You Must Know (from the syllabus):
• Metabolic terminology: flux, regulation, control of pathways.
• Glycolysis steps, enzymes, ATP yield, and regulation.
• Pyruvate fate & link to the citric acid (Krebs) cycle.
• Citric acid cycle reactions, key intermediates, coenzymes & energy carriers.
• Fatty acid β-oxidation — even vs odd chain; acetyl-CoA production.
• ATP production via the electron transport chain and oxidative phosphorylation. (Portage
Learning)
Module 7 – 50 Practice Questions (With Answer -s & Explanations)
Bioenergetics & Thermodynamics
1. True or False: A reaction with a negative ΔG is non-spontaneous.**
Answer -: False
Explanation: A negative ΔG means the reaction is spontaneous under standard conditions.
2.
3. What term describes the rate of flow through a metabolic pathway?
A. Capacity
B. Flux
C. Efficiency
D. Yield
, Answer -: B — Flux
Explanation: Flux describes how rapidly metabolites move through a pathway.
Glycolysis
3. Which enzyme catalyzes the first step of glycolysis (phosphorylation of glucose)?
A. Hexokinase
B. Phosphofructokinase
C. Aldolase
D. Pyruvate kinase
Answer -: A — Hexokinase
Explanation: Hexokinase converts glucose → glucose-6-phosphate using ATP.
4. How many ATP molecules are consumed in the energy-investment stage of glycolysis?
A. 1
B. 2
C. 3
D. 4
Answer -: B — 2
Explanation: Two ATPs are used (hexokinase and phosphofructokinase steps).
5. Which glycolytic step generates ATP via substrate-level phosphorylation?
A. Glucose → G6P
B. F1,6BP → G3P
C. 1,3-BPG → 3-PG
D. NAD+ → NADH
Answer -: C — 1,3-BPG to 3-PG
Explanation: This step directly produces ATP by phosphate transfer to ADP.
Pyruvate & Acetyl-CoA
6. Pyruvate enters the mitochondrion and is converted to acetyl-CoA by:
A. Pyruvate dehydrogenase
B. Lactate dehydrogenase
C. Pyruvate kinase
D. Transketolase
Answer -: A — Pyruvate dehydrogenase
Explanation: This irreversible reaction links glycolysis to the TCA cycle.
Citric Acid (Krebs) Cycle
7. Which molecule combines with acetyl-CoA to begin the citric acid cycle?
A. Oxaloacetate
, B. Citrate
C. Isocitrate
D. Malate
Answer -: A — Oxaloacetate
Explanation: Acetyl-CoA + oxaloacetate → citrate to start the cycle.
8. How many NADH are produced in one turn of the citric acid cycle?
A. 1
B. 2
C. 3
D. 4
Answer -: C — 3
Explanation: NADH from isocitrate DH, α-KG DH, and malate DH.
9. Which step directly produces GTP (or ATP) in the TCA cycle?
A. Isocitrate → α-ketoglutarate
B. Succinyl-CoA → succinate
C. Fumarate → malate
D. Malate → oxaloacetate
Answer -: B — Succinyl-CoA → succinate
Explanation: This step yields GTP via substrate-level phosphorylation.
Fatty Acid Oxidation (β-Oxidation)
10. β-Oxidation occurs in the:
A. Cytosol
B. Mitochondrial matrix
C. Endoplasmic reticulum
D. Nucleus
Answer -: B — Mitochondrial matrix
Explanation: Fatty acids are activated in cytosol then transported into mitochondria for
β-oxidation.
11. Each round of β-oxidation shortens a fatty acid chain by how many carbons?
A. 1
B. 2
C. 3
D. 4
Answer -: B — 2 carbons
Explanation: Each cycle removes an acetyl-CoA unit.
ATP Production & Oxidative Phosphorylation
