BIOCHEM 210 - PORTAGE
LEARNING EXAM MODULE 1-8
AND FINAL EXAM QUESTIONS
LATEST MOCK PRACTICE SET
190 Questions with Answers and Detailed Rationales
100 PERCENT GUARANTEED PASS
INSTANT DOWNLOAD ANSWERS INCLUDED
IMPORTANCE OF THIS DOCUMENT
This comprehensive examination preparation guide has been meticulously developed to help you succeed in the
BIOCHEM 210 - PORTAGE LEARNING EXAM MODULE 1-8 AND FINAL EXAM QUESTIONS AND VERIFIED
ANSWERS WITH RATIONALES.PDF. It contains 190 carefully selected questions that reflect the most current
exam content and testing strategies. Each question is accompanied by a correct answer and a detailed rationale
that explains the underlying pathophysiology, pharmacology, or clinical reasoning.
Self-Assessment – Test your knowledge and Exam Preparation – Familiarize yourself with the
identify areas requiring further question format and content
study areas
Concept Reinforcement – Deepen your Confidence Building – Develop test-taking
understanding through strategies and reduce
evidence-based exam anxiety
rationales
Time Management – Practice answering
questions under simulated
exam conditions
Review Summary 190 Questions
Foundations - Application - Biochem 210 Portage Learning Module 1-8 AND AND WITH Rationales PDF
Biochemistry Undergraduate YEAR 3
All answers with rationales
,Table of Contents
Section A - Enzyme Section B - Researcher
Questions 1 to 48 Questions 49 to 96
Section C - Likely Section D - Metabolic
Questions 97 to 144 Questions 145 to 190
,Section A - Enzyme
Q1.
In a patient with a mitochondrial defect that impairs the oxidation of NADH, the cytosolic
ratio of NADH/NAD+ rises. Which of the following best explains how this affects the
malate-aspartate shuttle and the rate of glycolysis?
A. Increased cytosolic NADH inhibits the B. Increased cytosolic NADH activates the
malate dehydrogenase reaction, reducing aspartate aminotransferase, enhancing
shuttle capacity and forcing glycolysis to rely shuttle activity and increasing the rate of
on lactate dehydrogenase to regenerate glycolysis.
NAD+.
C. Increased cytosolic NADH promotes the D. Increased cytosolic NADH directly
reduction of oxaloacetate to malate, which is inhibits phosphofructokinase-1, slowing
then transported into the mitochondria, thus glycolysis and preventing further NADH
maintaining shuttle function and glycolysis. accumulation.
Correct: A - Increased cytosolic NADH inhibits the malate dehydrogenase reaction,
reducing shuttle capacity and forcing glycolysis to rely on lactate dehydrogenase to
regenerate NAD+.
Rationale:The malate-aspartate shuttle relies on a favorable cytosolic NADH/NAD+ ratio to
drive malate dehydrogenase toward malate production. When NADH accumulates, the
reaction becomes thermodynamically unfavorable, reducing shuttle activity. Consequently,
glycolysis must use lactate dehydrogenase to regenerate NAD+, which is the correct answer.
Choice C is incorrect because the reaction is actually inhibited. Choices B and D
misrepresent the regulatory effects.
Q2.
A researcher discovers a new enzyme that catalyzes the reaction A -> B with a Keq of 0.5.
In the cell, [A] = 2 mM and [B] = 0.5 mM. If the enzyme's Vmax is 100 mol/min, what is the
direction and approximate rate of the reaction at this substrate concentration, assuming
the Michaelis-Menten model?
A. Forward direction, rate 50 mol/min B. Reverse direction, rate 50 mol/min
C. Forward direction, rate 100 mol/min D. Reverse direction, rate 100 mol/min
Correct: A - Forward direction, rate 50 mol/min
Page 3
, Section A - Enzyme
Rationale: The actual free energy change (”G) determines the direction, not Keq alone. With
Keq = 0.5, the reaction favors reactants at equilibrium. However, the cellular concentrations
give a mass action ratio Q = [B]/[A] = 0.25, which is less than Keq, so the reaction proceeds
forward to reach equilibrium. The rate depends on substrate concentration relative to Km;
assuming [A] is near saturating, the rate approaches Vmax, but the given values are
insufficient to calculate exact rate. The best answer is A because the forward direction is
correct, and the rate is approximated by Vmax. Choice B is wrong direction. C overestimates
rate without Km. D is wrong direction and overestimates.
Q3.
Which of the following experimental results would most directly challenge the
chemiosmotic theory of oxidative phosphorylation?
A. ATP synthesis is observed in the absence B. Uncouplers like 2,4-dinitrophenol abolish
of a proton gradient if a pH jump is artificially ATP synthesis while oxygen consumption
applied. continues.
C. Oligomycin inhibits both oxygen D. Submitochondrial particles can
consumption and ATP synthesis. synthesize ATP when provided with NADH
and oxygen.
Correct: A - ATP synthesis is observed in the absence of a proton gradient if a pH jump is
artificially applied.
Rationale:The chemiosmotic theory posits that the proton gradient is essential for ATP
synthesis. If ATP synthesis occurs without a gradient (and without a pH jump to artificially
create one), it would contradict the theory. Choice A is correct. Choices B, C, and D are
consistent with the theory: uncouplers dissipate the gradient, oligomycin blocks the ATP
synthase, and submitochondrial particles can pump protons to create a gradient.
Q4.
A compound is added to a cell-free translation system that prevents the dissociation of
the 70S ribosome after termination. Which of the following processes is directly inhibited?
A. Binding of release factors to the A site B. Hydrolysis of the ester bond between the
completed polypeptide and tRNA
C. Recycling of ribosomal subunits for a new D. Translocation of the peptidyl-tRNA from
round of initiation the A site to the P site
Correct: C - Recycling of ribosomal subunits for a new round of initiation
Page 4
LEARNING EXAM MODULE 1-8
AND FINAL EXAM QUESTIONS
LATEST MOCK PRACTICE SET
190 Questions with Answers and Detailed Rationales
100 PERCENT GUARANTEED PASS
INSTANT DOWNLOAD ANSWERS INCLUDED
IMPORTANCE OF THIS DOCUMENT
This comprehensive examination preparation guide has been meticulously developed to help you succeed in the
BIOCHEM 210 - PORTAGE LEARNING EXAM MODULE 1-8 AND FINAL EXAM QUESTIONS AND VERIFIED
ANSWERS WITH RATIONALES.PDF. It contains 190 carefully selected questions that reflect the most current
exam content and testing strategies. Each question is accompanied by a correct answer and a detailed rationale
that explains the underlying pathophysiology, pharmacology, or clinical reasoning.
Self-Assessment – Test your knowledge and Exam Preparation – Familiarize yourself with the
identify areas requiring further question format and content
study areas
Concept Reinforcement – Deepen your Confidence Building – Develop test-taking
understanding through strategies and reduce
evidence-based exam anxiety
rationales
Time Management – Practice answering
questions under simulated
exam conditions
Review Summary 190 Questions
Foundations - Application - Biochem 210 Portage Learning Module 1-8 AND AND WITH Rationales PDF
Biochemistry Undergraduate YEAR 3
All answers with rationales
,Table of Contents
Section A - Enzyme Section B - Researcher
Questions 1 to 48 Questions 49 to 96
Section C - Likely Section D - Metabolic
Questions 97 to 144 Questions 145 to 190
,Section A - Enzyme
Q1.
In a patient with a mitochondrial defect that impairs the oxidation of NADH, the cytosolic
ratio of NADH/NAD+ rises. Which of the following best explains how this affects the
malate-aspartate shuttle and the rate of glycolysis?
A. Increased cytosolic NADH inhibits the B. Increased cytosolic NADH activates the
malate dehydrogenase reaction, reducing aspartate aminotransferase, enhancing
shuttle capacity and forcing glycolysis to rely shuttle activity and increasing the rate of
on lactate dehydrogenase to regenerate glycolysis.
NAD+.
C. Increased cytosolic NADH promotes the D. Increased cytosolic NADH directly
reduction of oxaloacetate to malate, which is inhibits phosphofructokinase-1, slowing
then transported into the mitochondria, thus glycolysis and preventing further NADH
maintaining shuttle function and glycolysis. accumulation.
Correct: A - Increased cytosolic NADH inhibits the malate dehydrogenase reaction,
reducing shuttle capacity and forcing glycolysis to rely on lactate dehydrogenase to
regenerate NAD+.
Rationale:The malate-aspartate shuttle relies on a favorable cytosolic NADH/NAD+ ratio to
drive malate dehydrogenase toward malate production. When NADH accumulates, the
reaction becomes thermodynamically unfavorable, reducing shuttle activity. Consequently,
glycolysis must use lactate dehydrogenase to regenerate NAD+, which is the correct answer.
Choice C is incorrect because the reaction is actually inhibited. Choices B and D
misrepresent the regulatory effects.
Q2.
A researcher discovers a new enzyme that catalyzes the reaction A -> B with a Keq of 0.5.
In the cell, [A] = 2 mM and [B] = 0.5 mM. If the enzyme's Vmax is 100 mol/min, what is the
direction and approximate rate of the reaction at this substrate concentration, assuming
the Michaelis-Menten model?
A. Forward direction, rate 50 mol/min B. Reverse direction, rate 50 mol/min
C. Forward direction, rate 100 mol/min D. Reverse direction, rate 100 mol/min
Correct: A - Forward direction, rate 50 mol/min
Page 3
, Section A - Enzyme
Rationale: The actual free energy change (”G) determines the direction, not Keq alone. With
Keq = 0.5, the reaction favors reactants at equilibrium. However, the cellular concentrations
give a mass action ratio Q = [B]/[A] = 0.25, which is less than Keq, so the reaction proceeds
forward to reach equilibrium. The rate depends on substrate concentration relative to Km;
assuming [A] is near saturating, the rate approaches Vmax, but the given values are
insufficient to calculate exact rate. The best answer is A because the forward direction is
correct, and the rate is approximated by Vmax. Choice B is wrong direction. C overestimates
rate without Km. D is wrong direction and overestimates.
Q3.
Which of the following experimental results would most directly challenge the
chemiosmotic theory of oxidative phosphorylation?
A. ATP synthesis is observed in the absence B. Uncouplers like 2,4-dinitrophenol abolish
of a proton gradient if a pH jump is artificially ATP synthesis while oxygen consumption
applied. continues.
C. Oligomycin inhibits both oxygen D. Submitochondrial particles can
consumption and ATP synthesis. synthesize ATP when provided with NADH
and oxygen.
Correct: A - ATP synthesis is observed in the absence of a proton gradient if a pH jump is
artificially applied.
Rationale:The chemiosmotic theory posits that the proton gradient is essential for ATP
synthesis. If ATP synthesis occurs without a gradient (and without a pH jump to artificially
create one), it would contradict the theory. Choice A is correct. Choices B, C, and D are
consistent with the theory: uncouplers dissipate the gradient, oligomycin blocks the ATP
synthase, and submitochondrial particles can pump protons to create a gradient.
Q4.
A compound is added to a cell-free translation system that prevents the dissociation of
the 70S ribosome after termination. Which of the following processes is directly inhibited?
A. Binding of release factors to the A site B. Hydrolysis of the ester bond between the
completed polypeptide and tRNA
C. Recycling of ribosomal subunits for a new D. Translocation of the peptidyl-tRNA from
round of initiation the A site to the P site
Correct: C - Recycling of ribosomal subunits for a new round of initiation
Page 4
