BIOCHEM 210 MODULE 7 PRACTICE EXAM
2026 | METABOLISM (GLYCOLYSIS, CITRIC
ACID CYCLE & OXIDATIVE
PHOSPHORYLATION) QUESTIONS, VERIFIED
ANSWERS & EXPLANATIONS STUDY GUIDE
PDF
BIOCHEM 210 MODULE 7 PRACTICE EXAM 2026 | METABOLISM STUDY GUIDE
DOCUMENT OVERVIEW:
• This practice exam contains 200 verified multiple-choice questions designed to
strengthen your mastery of glycolysis, the citric acid cycle, and oxidative
phosphorylation through comprehensive coverage of mechanisms, enzymes,
regulation, and energy production.
• Study this material by reviewing each question, attempting the answer before
reading the EXPERT RATIONALE, and using the explanations to reinforce
biochemical concepts and test-taking strategies.
SECTION 1: GLYCOLYSIS
Question 1: Which enzyme catalyzes the first committed step of glycolysis,
converting glucose-6-phosphate to fructose-6-phosphate?
A) Hexokinase
B) Phosphofructokinase-1
C) Phosphoglucose isomerase
D) Aldolase
E) Enolase
CORRECT ANSWER: C
Phosphoglucose isomerase catalyzes the reversible isomerization of glucose-6-
phosphate to fructose-6-phosphate. This is an early step in glycolysis but not the
,committed step; phosphofructokinase-1 catalyzes the first committed and rate-
limiting step.
Question 2: What is the primary regulatory enzyme of glycolysis that is
inhibited by ATP and citrate but activated by AMP and ADP?
A) Hexokinase
B) Enolase
C) Aldolase
D) Phosphofructokinase-1
E) Pyruvate kinase
CORRECT ANSWER: D
Phosphofructokinase-1 (PFK-1) is the rate-limiting enzyme of glycolysis and the
primary regulatory point. It is allosterically inhibited by ATP and citrate (indicating
sufficient energy) and activated by AMP and ADP (indicating energy depletion).
Question 3: In glycolysis, the conversion of glyceraldehyde-3-phosphate to 1,3-
bisphosphoglycerate is catalyzed by which enzyme?
A) Triose phosphate isomerase
B) Glyceraldehyde-3-phosphate dehydrogenase
C) Phosphoglycerate kinase
D) Phosphoglycerate mutase
E) Enolase
CORRECT ANSWER: B
Glyceraldehyde-3-phosphate dehydrogenase catalyzes the oxidation of
glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, coupled with NAD+
reduction to NADH. This is the only redox step in glycolysis.
,Question 4: How many ATP molecules are generated per glucose molecule
during the payoff phase of glycolysis?
A) 1
B) 2
C) 3
D) 4
E) 6
CORRECT ANSWER: D
During the payoff phase (second half of glycolysis), two molecules of 1,3-
bisphosphoglycerate are converted to pyruvate, yielding 4 ATP total (2 ATP from
phosphoglycerate kinase and 2 ATP from pyruvate kinase reactions).
Question 5: What is the net ATP gain from glycolysis under anaerobic
conditions?
A) 0
B) 1
C) 2
D) 3
E) 4
CORRECT ANSWER: C
The net ATP gain is 2 ATP per glucose molecule (4 ATP produced in payoff phase
minus 2 ATP consumed in preparatory phase). Under anaerobic conditions, NADH
is regenerated through lactate formation.
, Question 6: Which enzyme catalyzes the conversion of pyruvate to lactate
during anaerobic glycolysis?
A) Pyruvate carboxylase
B) Lactate dehydrogenase
C) Alanine aminotransferase
D) Pyruvate kinase
E) Alcohol dehydrogenase
CORRECT ANSWER: B
Lactate dehydrogenase catalyzes the reversible conversion of pyruvate to lactate,
regenerating NAD+ from NADH. This allows glycolysis to continue under anaerobic
conditions.
Question 7: What is the Km value significance of hexokinase for glucose?
A) Very high Km means glucose enters cells only when blood glucose is very high
B) Low Km means hexokinase is saturated at normal blood glucose levels
C) Km is irrelevant to hexokinase function
D) High Km ensures glucose is only phosphorylated during fed state
E) Km of hexokinase prevents glucose-6-phosphate accumulation
CORRECT ANSWER: B
Hexokinase has a low Km for glucose (approximately 0.1 mM), meaning it is nearly
saturated at normal blood glucose levels (5 mM). This allows efficient trapping of
glucose in cells as glucose-6-phosphate.
Question 8: Which of the following is NOT a regulatory mechanism of
phosphofructokinase-1?
A) Allosteric inhibition by ATP
2026 | METABOLISM (GLYCOLYSIS, CITRIC
ACID CYCLE & OXIDATIVE
PHOSPHORYLATION) QUESTIONS, VERIFIED
ANSWERS & EXPLANATIONS STUDY GUIDE
BIOCHEM 210 MODULE 7 PRACTICE EXAM 2026 | METABOLISM STUDY GUIDE
DOCUMENT OVERVIEW:
• This practice exam contains 200 verified multiple-choice questions designed to
strengthen your mastery of glycolysis, the citric acid cycle, and oxidative
phosphorylation through comprehensive coverage of mechanisms, enzymes,
regulation, and energy production.
• Study this material by reviewing each question, attempting the answer before
reading the EXPERT RATIONALE, and using the explanations to reinforce
biochemical concepts and test-taking strategies.
SECTION 1: GLYCOLYSIS
Question 1: Which enzyme catalyzes the first committed step of glycolysis,
converting glucose-6-phosphate to fructose-6-phosphate?
A) Hexokinase
B) Phosphofructokinase-1
C) Phosphoglucose isomerase
D) Aldolase
E) Enolase
CORRECT ANSWER: C
Phosphoglucose isomerase catalyzes the reversible isomerization of glucose-6-
phosphate to fructose-6-phosphate. This is an early step in glycolysis but not the
,committed step; phosphofructokinase-1 catalyzes the first committed and rate-
limiting step.
Question 2: What is the primary regulatory enzyme of glycolysis that is
inhibited by ATP and citrate but activated by AMP and ADP?
A) Hexokinase
B) Enolase
C) Aldolase
D) Phosphofructokinase-1
E) Pyruvate kinase
CORRECT ANSWER: D
Phosphofructokinase-1 (PFK-1) is the rate-limiting enzyme of glycolysis and the
primary regulatory point. It is allosterically inhibited by ATP and citrate (indicating
sufficient energy) and activated by AMP and ADP (indicating energy depletion).
Question 3: In glycolysis, the conversion of glyceraldehyde-3-phosphate to 1,3-
bisphosphoglycerate is catalyzed by which enzyme?
A) Triose phosphate isomerase
B) Glyceraldehyde-3-phosphate dehydrogenase
C) Phosphoglycerate kinase
D) Phosphoglycerate mutase
E) Enolase
CORRECT ANSWER: B
Glyceraldehyde-3-phosphate dehydrogenase catalyzes the oxidation of
glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, coupled with NAD+
reduction to NADH. This is the only redox step in glycolysis.
,Question 4: How many ATP molecules are generated per glucose molecule
during the payoff phase of glycolysis?
A) 1
B) 2
C) 3
D) 4
E) 6
CORRECT ANSWER: D
During the payoff phase (second half of glycolysis), two molecules of 1,3-
bisphosphoglycerate are converted to pyruvate, yielding 4 ATP total (2 ATP from
phosphoglycerate kinase and 2 ATP from pyruvate kinase reactions).
Question 5: What is the net ATP gain from glycolysis under anaerobic
conditions?
A) 0
B) 1
C) 2
D) 3
E) 4
CORRECT ANSWER: C
The net ATP gain is 2 ATP per glucose molecule (4 ATP produced in payoff phase
minus 2 ATP consumed in preparatory phase). Under anaerobic conditions, NADH
is regenerated through lactate formation.
, Question 6: Which enzyme catalyzes the conversion of pyruvate to lactate
during anaerobic glycolysis?
A) Pyruvate carboxylase
B) Lactate dehydrogenase
C) Alanine aminotransferase
D) Pyruvate kinase
E) Alcohol dehydrogenase
CORRECT ANSWER: B
Lactate dehydrogenase catalyzes the reversible conversion of pyruvate to lactate,
regenerating NAD+ from NADH. This allows glycolysis to continue under anaerobic
conditions.
Question 7: What is the Km value significance of hexokinase for glucose?
A) Very high Km means glucose enters cells only when blood glucose is very high
B) Low Km means hexokinase is saturated at normal blood glucose levels
C) Km is irrelevant to hexokinase function
D) High Km ensures glucose is only phosphorylated during fed state
E) Km of hexokinase prevents glucose-6-phosphate accumulation
CORRECT ANSWER: B
Hexokinase has a low Km for glucose (approximately 0.1 mM), meaning it is nearly
saturated at normal blood glucose levels (5 mM). This allows efficient trapping of
glucose in cells as glucose-6-phosphate.
Question 8: Which of the following is NOT a regulatory mechanism of
phosphofructokinase-1?
A) Allosteric inhibition by ATP
