C785 Biochemistry - Module 5 Study Guide 2026 |WGU
1. Where does glycolysis occur in the cell?
A. Cytosol
B. Mitochondrial matrix
C. Inner mitochondrial membrane
D. Endoplasmic reticulum
Answer: A
Rationale: Glycolysis is the metabolic pathway that converts glucose into pyruvate and
occurs entirely within the cytosol of the cell.
2. What is the net yield of ATP molecules per molecule of glucose during
anaerobic glycolysis?
A. 36 ATP
B. 4 ATP
C. 32 ATP
D. 2 ATP
Answer: D
Rationale: Anaerobic glycolysis produces a gross of 4 ATP but consumes 2 ATP in the
investment phase, resulting in a net yield of 2 ATP.
3. Which enzyme is the primary rate-limiting step of glycolysis?
A. Hexokinase
B. Pyruvate kinase
C. Phosphofructokinase-1 (PFK-1)
D. Aldolase
Answer: C
,Rationale: PFK-1 is the key regulatory enzyme in glycolysis, controlled by ATP levels and
fructose-2,6-bisphosphate.
4. Under anaerobic conditions, pyruvate is converted into which molecule in
human muscle cells?
A. Ethanol
B. Acetyl-CoA
C. Lactate
D. Oxaloacetate
Answer: C
Rationale: In the absence of oxygen, lactate dehydrogenase reduces pyruvate to lactate to
regenerate NAD+ for glycolysis to continue.
5. Which of the following molecules is a potent activator of PFK-1?
A. Citrate
B. Fructose-2,6-bisphosphate
C. ATP
D. Glucagon
Answer: B
Rationale: Fructose-2,6-bisphosphate is a powerful allosteric activator of PFK-1,
overriding the inhibitory effects of ATP.
6. What is the function of the Cori Cycle?
A. To produce glucose from fatty acids
B. To synthesize urea from ammonia
C. To break down glycogen in the brain
D. To transport lactate from muscle to liver for gluconeogenesis
Answer: D
Rationale: The Cori Cycle involves the transport of lactate to the liver, where it is
converted back into glucose via gluconeogenesis and returned to the muscle.
, 7. Which enzyme catalyzes the conversion of pyruvate to Acetyl-CoA?
A. Pyruvate dehydrogenase complex
B. Pyruvate carboxylase
C. Lactate dehydrogenase
D. Phosphoenolpyruvate carboxykinase
Answer: A
Rationale: The Pyruvate Dehydrogenase Complex (PDC) performs the oxidative
decarboxylation of pyruvate into Acetyl-CoA inside the mitochondria.
8. How many molecules of NADH are produced in one single turn of the Citric
Acid Cycle?
A. 1
B. 2
C. 3
D. 4
Answer: C
Rationale: One turn of the Citric Acid Cycle produces 3 NADH, 1 FADH2, and 1 GTP (or
ATP).
9. Where are the enzymes of the Citric Acid Cycle located?
A. Cytosol
B. Inner mitochondrial membrane
C. Mitochondrial matrix
D. Intermembrane space
Answer: C
Rationale: Most enzymes of the Citric Acid Cycle are found in the mitochondrial matrix,
except for succinate dehydrogenase.
1. Where does glycolysis occur in the cell?
A. Cytosol
B. Mitochondrial matrix
C. Inner mitochondrial membrane
D. Endoplasmic reticulum
Answer: A
Rationale: Glycolysis is the metabolic pathway that converts glucose into pyruvate and
occurs entirely within the cytosol of the cell.
2. What is the net yield of ATP molecules per molecule of glucose during
anaerobic glycolysis?
A. 36 ATP
B. 4 ATP
C. 32 ATP
D. 2 ATP
Answer: D
Rationale: Anaerobic glycolysis produces a gross of 4 ATP but consumes 2 ATP in the
investment phase, resulting in a net yield of 2 ATP.
3. Which enzyme is the primary rate-limiting step of glycolysis?
A. Hexokinase
B. Pyruvate kinase
C. Phosphofructokinase-1 (PFK-1)
D. Aldolase
Answer: C
,Rationale: PFK-1 is the key regulatory enzyme in glycolysis, controlled by ATP levels and
fructose-2,6-bisphosphate.
4. Under anaerobic conditions, pyruvate is converted into which molecule in
human muscle cells?
A. Ethanol
B. Acetyl-CoA
C. Lactate
D. Oxaloacetate
Answer: C
Rationale: In the absence of oxygen, lactate dehydrogenase reduces pyruvate to lactate to
regenerate NAD+ for glycolysis to continue.
5. Which of the following molecules is a potent activator of PFK-1?
A. Citrate
B. Fructose-2,6-bisphosphate
C. ATP
D. Glucagon
Answer: B
Rationale: Fructose-2,6-bisphosphate is a powerful allosteric activator of PFK-1,
overriding the inhibitory effects of ATP.
6. What is the function of the Cori Cycle?
A. To produce glucose from fatty acids
B. To synthesize urea from ammonia
C. To break down glycogen in the brain
D. To transport lactate from muscle to liver for gluconeogenesis
Answer: D
Rationale: The Cori Cycle involves the transport of lactate to the liver, where it is
converted back into glucose via gluconeogenesis and returned to the muscle.
, 7. Which enzyme catalyzes the conversion of pyruvate to Acetyl-CoA?
A. Pyruvate dehydrogenase complex
B. Pyruvate carboxylase
C. Lactate dehydrogenase
D. Phosphoenolpyruvate carboxykinase
Answer: A
Rationale: The Pyruvate Dehydrogenase Complex (PDC) performs the oxidative
decarboxylation of pyruvate into Acetyl-CoA inside the mitochondria.
8. How many molecules of NADH are produced in one single turn of the Citric
Acid Cycle?
A. 1
B. 2
C. 3
D. 4
Answer: C
Rationale: One turn of the Citric Acid Cycle produces 3 NADH, 1 FADH2, and 1 GTP (or
ATP).
9. Where are the enzymes of the Citric Acid Cycle located?
A. Cytosol
B. Inner mitochondrial membrane
C. Mitochondrial matrix
D. Intermembrane space
Answer: C
Rationale: Most enzymes of the Citric Acid Cycle are found in the mitochondrial matrix,
except for succinate dehydrogenase.
