CHEM 210 Module 7 - 2026/2027 | Page 1
,CHEM 210 Module 7 Exam | Biochemistry |
Portage Learning | Q & A | 2026/2027 Actual
Original practice assessment aligned to the public CHEM 210 Module 7 syllabus
1. A reaction has a standard transformed free-energy change of +18 kJ/mol, but cellular concentrations make the
actual ΔG negative. What follows from this condition?
A) The reaction must be enzyme-catalyzed before ΔG can become negative.
B) The reaction is at equilibrium because ΔG°′ is positive.
C) The reaction can proceed spontaneously in the forward direction under those cellular conditions.
D) The reaction cannot proceed forward unless ATP is consumed directly.
Correct Answer: The reaction can proceed spontaneously in the forward direction under those cellular conditions.
Rationale: The reaction can proceed spontaneously in the forward direction under those cellular conditions. is
correct. This follows because spontaneity depends on the actual ΔG, which includes reactant and product
concentrations. The distractors conflict with enzymes change rates but not thermodynamic favorability, equilibrium
requires ΔG = 0. Therefore, the pathway sequence, stoichiometry, and energy logic support this answer for Module
7 metabolism.
2. During steady-state metabolism, the concentration of an intermediate remains nearly constant even though
molecules continuously enter and leave its pool. Which description best fits this observation? A) Its pathway is at
thermodynamic equilibrium.
B) Its concentration must be zero.
C) Its rate of formation is approximately equal to its rate of consumption.
D) Its producing enzyme is completely inhibited.
Correct Answer: Its rate of formation is approximately equal to its rate of consumption.
Rationale: Its rate of formation is approximately equal to its rate of consumption. is correct. This follows because
steady state means opposing pathway rates balance closely enough. The distractors conflict with steady state is not
identical to equilibrium, a. Therefore, the pathway sequence, stoichiometry, cofactor roles, and energy logic
support this answer for Module 7 metabolism.
3. Suppose a pathway intermediate accumulates sharply after one enzyme is inhibited. What is the most direct
interpretation?
A) The inhibited enzyme normally produces the accumulating intermediate.
B) The inhibited step normally consumes that intermediate or a closely downstream form of it.
C) All upstream reactions have stopped.
D) The pathway has necessarily reached equilibrium.
Correct Answer: The inhibited step normally consumes that intermediate or a closely downstream form of it.
Rationale: The inhibited step normally consumes that intermediate or a closely downstream form of it. is correct.
This follows because blocking a consuming step commonly causes substrate to build up. The distractors conflict with
blocking a producing step would usually lower. Therefore, pathway sequence and energy logic support this Module
7 answer.
4. An enzyme-catalyzed step operates far from equilibrium and has a large negative ΔG in vivo. Why is this step a
likely regulatory site?
CHEM 210 Module 7 - 2026/2027 | Page 2
, A) The reaction automatically runs at the same rate in both directions.
B) Its equilibrium constant must equal one.
C) Its activity cannot respond to allosteric effectors.
D) Changes in its activity can strongly influence pathway flux because the reaction is effectively irreversible under
cellular conditions.
Correct Answer: Changes in its activity can strongly influence pathway flux because the reaction is effectively
irreversible under cellular conditions.
Rationale: Changes in its activity can strongly influence pathway flux because the reaction is effectively irreversible
under cellular conditions. is correct. This follows because far-from-equilibrium reactions have substantial
thermodynamic driving force and often serve. The distractors conflict with reversible nearequilibrium steps behave
differently, K need not. Therefore, pathway sequence and energy logic support this Module 7 answer.
5. A cell couples an endergonic reaction to ATP hydrolysis. What is the thermodynamic requirement for the coupled
process to proceed spontaneously?
A) The endergonic reaction must have a negative ΔG by itself.
B) ATP hydrolysis must occur in a different cellular compartment.
C) The enzyme must make the equilibrium constant equal to one.
D) The sum of the ΔG values for the coupled reactions must be negative.
Correct Answer: The sum of the ΔG values for the coupled reactions must be negative.
Rationale: The sum of the ΔG values for the coupled reactions must be negative. is correct. This follows because
free-energy changes are additive, so favorable ATP hydrolysis can outweigh. The distractors conflict with the
uncoupled reaction may remain endergonic, compartment separation. Therefore, pathway sequence and energy
logic support this Module 7 answer.
6. A metabolic pathway contains a branch point where one intermediate can enter either energy production or
biosynthesis. What most directly determines flux through each branch? A) The alphabetical order of enzyme names.
B) The molecular mass of the branch-point metabolite alone.
C) Whether every reaction in both branches is irreversible.
D) Relative enzyme activities, substrate availability, and regulatory signals at the competing branch reactions.
Correct Answer: Relative enzyme activities, substrate availability, and regulatory signals at the competing branch
reactions.
Rationale: Relative enzyme activities, substrate availability, and regulatory signals at the competing branch
reactions. is correct. This follows because branch flux reflects kinetic competition and regulation acting on enzymes.
The distractors conflict with nomenclature has no mechanistic effect, molecular mass alone. Therefore, pathway
sequence and energy logic support this Module 7 answer.
7. When ATP and NADH are abundant, many oxidative pathways slow. Which regulatory logic does this illustrate?
A) Feedback signaling that cellular energy supply is sufficient and additional fuel oxidation can be reduced.
B) Feedforward activation caused by product depletion.
C) Substrate-level phosphorylation becoming impossible.
D) Loss of all enzyme specificity.
Correct Answer: Feedback signaling that cellular energy supply is sufficient and additional fuel oxidation can be
reduced.
Rationale: Feedback signaling that cellular energy supply is sufficient and additional fuel oxidation can be reduced.
is correct. This follows because high-energy products often inhibit key oxidative enzymes to match catabolic. The
CHEM 210 Module 7 - 2026/2027 | Page 3
,CHEM 210 Module 7 Exam | Biochemistry |
Portage Learning | Q & A | 2026/2027 Actual
Original practice assessment aligned to the public CHEM 210 Module 7 syllabus
1. A reaction has a standard transformed free-energy change of +18 kJ/mol, but cellular concentrations make the
actual ΔG negative. What follows from this condition?
A) The reaction must be enzyme-catalyzed before ΔG can become negative.
B) The reaction is at equilibrium because ΔG°′ is positive.
C) The reaction can proceed spontaneously in the forward direction under those cellular conditions.
D) The reaction cannot proceed forward unless ATP is consumed directly.
Correct Answer: The reaction can proceed spontaneously in the forward direction under those cellular conditions.
Rationale: The reaction can proceed spontaneously in the forward direction under those cellular conditions. is
correct. This follows because spontaneity depends on the actual ΔG, which includes reactant and product
concentrations. The distractors conflict with enzymes change rates but not thermodynamic favorability, equilibrium
requires ΔG = 0. Therefore, the pathway sequence, stoichiometry, and energy logic support this answer for Module
7 metabolism.
2. During steady-state metabolism, the concentration of an intermediate remains nearly constant even though
molecules continuously enter and leave its pool. Which description best fits this observation? A) Its pathway is at
thermodynamic equilibrium.
B) Its concentration must be zero.
C) Its rate of formation is approximately equal to its rate of consumption.
D) Its producing enzyme is completely inhibited.
Correct Answer: Its rate of formation is approximately equal to its rate of consumption.
Rationale: Its rate of formation is approximately equal to its rate of consumption. is correct. This follows because
steady state means opposing pathway rates balance closely enough. The distractors conflict with steady state is not
identical to equilibrium, a. Therefore, the pathway sequence, stoichiometry, cofactor roles, and energy logic
support this answer for Module 7 metabolism.
3. Suppose a pathway intermediate accumulates sharply after one enzyme is inhibited. What is the most direct
interpretation?
A) The inhibited enzyme normally produces the accumulating intermediate.
B) The inhibited step normally consumes that intermediate or a closely downstream form of it.
C) All upstream reactions have stopped.
D) The pathway has necessarily reached equilibrium.
Correct Answer: The inhibited step normally consumes that intermediate or a closely downstream form of it.
Rationale: The inhibited step normally consumes that intermediate or a closely downstream form of it. is correct.
This follows because blocking a consuming step commonly causes substrate to build up. The distractors conflict with
blocking a producing step would usually lower. Therefore, pathway sequence and energy logic support this Module
7 answer.
4. An enzyme-catalyzed step operates far from equilibrium and has a large negative ΔG in vivo. Why is this step a
likely regulatory site?
CHEM 210 Module 7 - 2026/2027 | Page 2
, A) The reaction automatically runs at the same rate in both directions.
B) Its equilibrium constant must equal one.
C) Its activity cannot respond to allosteric effectors.
D) Changes in its activity can strongly influence pathway flux because the reaction is effectively irreversible under
cellular conditions.
Correct Answer: Changes in its activity can strongly influence pathway flux because the reaction is effectively
irreversible under cellular conditions.
Rationale: Changes in its activity can strongly influence pathway flux because the reaction is effectively irreversible
under cellular conditions. is correct. This follows because far-from-equilibrium reactions have substantial
thermodynamic driving force and often serve. The distractors conflict with reversible nearequilibrium steps behave
differently, K need not. Therefore, pathway sequence and energy logic support this Module 7 answer.
5. A cell couples an endergonic reaction to ATP hydrolysis. What is the thermodynamic requirement for the coupled
process to proceed spontaneously?
A) The endergonic reaction must have a negative ΔG by itself.
B) ATP hydrolysis must occur in a different cellular compartment.
C) The enzyme must make the equilibrium constant equal to one.
D) The sum of the ΔG values for the coupled reactions must be negative.
Correct Answer: The sum of the ΔG values for the coupled reactions must be negative.
Rationale: The sum of the ΔG values for the coupled reactions must be negative. is correct. This follows because
free-energy changes are additive, so favorable ATP hydrolysis can outweigh. The distractors conflict with the
uncoupled reaction may remain endergonic, compartment separation. Therefore, pathway sequence and energy
logic support this Module 7 answer.
6. A metabolic pathway contains a branch point where one intermediate can enter either energy production or
biosynthesis. What most directly determines flux through each branch? A) The alphabetical order of enzyme names.
B) The molecular mass of the branch-point metabolite alone.
C) Whether every reaction in both branches is irreversible.
D) Relative enzyme activities, substrate availability, and regulatory signals at the competing branch reactions.
Correct Answer: Relative enzyme activities, substrate availability, and regulatory signals at the competing branch
reactions.
Rationale: Relative enzyme activities, substrate availability, and regulatory signals at the competing branch
reactions. is correct. This follows because branch flux reflects kinetic competition and regulation acting on enzymes.
The distractors conflict with nomenclature has no mechanistic effect, molecular mass alone. Therefore, pathway
sequence and energy logic support this Module 7 answer.
7. When ATP and NADH are abundant, many oxidative pathways slow. Which regulatory logic does this illustrate?
A) Feedback signaling that cellular energy supply is sufficient and additional fuel oxidation can be reduced.
B) Feedforward activation caused by product depletion.
C) Substrate-level phosphorylation becoming impossible.
D) Loss of all enzyme specificity.
Correct Answer: Feedback signaling that cellular energy supply is sufficient and additional fuel oxidation can be
reduced.
Rationale: Feedback signaling that cellular energy supply is sufficient and additional fuel oxidation can be reduced.
is correct. This follows because high-energy products often inhibit key oxidative enzymes to match catabolic. The
CHEM 210 Module 7 - 2026/2027 | Page 3
