BioChem 210 Module 7 Exam - Portage Learning Latest Update 2026
Section 1: Core Concepts & Energetics (Questions 1-30)
1. A researcher measures enzyme activity at increasing substrate concentrations
and notices the reaction rate eventually plateaus. What BEST explains this
observation?
A. Substrate inhibition
B. Enzyme saturation at maximum velocity
C. Protein denaturation
D. Competitive inhibition
Answer: B. Enzyme saturation at maximum velocity
Rationale: At high substrate concentrations, all active sites of the enzyme become
occupied, reaching a maximum velocity (Vmax).
2. What is the sign (+ or -) of ΔG for the breakdown of ATP to ADP? Why is this
significant?
A. (+) Positive; it requires energy input
B. (-) Negative; it is spontaneous and can power other cellular processes
C. (+) Positive; it stores energy for later use
D. (-) Negative; it indicates the reaction is at equilibrium
,Answer: B. (-) Negative; it is spontaneous and can power other processes
Rationale: A negative ΔG indicates an exergonic (spontaneous) reaction, meaning
energy is released. This released energy is harnessed by the cell to drive
endergonic (non-spontaneous) reactions.
3. Which metabolic pathway primarily generates ATP under strictly anaerobic
conditions?
A. Citric acid cycle
B. Electron transport chain
C. Glycolysis
D. Beta-oxidation
Answer: C. Glycolysis
*Rationale: Glycolysis does not require oxygen and produces a net gain of 2 ATP
via substrate-level phosphorylation.*
4. A deficiency in niacin (Vitamin B3) would most directly impair the production of
which molecule necessary for cellular respiration?
A. FADH2
B. NADH
C. Acetyl-CoA
,D. H2O
Answer: B. NADH
Rationale: Niacin is a precursor for NAD+ and NADP+. NAD+ is the oxidized form
that accepts electrons to become NADH, a crucial electron carrier.
5. Which statement best describes the role of oxygen in aerobic respiration?
A. It is the final electron acceptor in the electron transport chain
B. It directly phosphorylates ADP to form ATP
C. It is necessary for the reactions of glycolysis to proceed
D. It combines with carbon to form CO2 in the CAC
Answer: A. It is the final electron acceptor in the electron transport chain
Rationale: Oxygen has high electronegativity and accepts electrons at the end of
the ETC, combining with protons to form water. Without it, the ETC halts.
6. A patient has elevated blood lactate after intense exercise. What biochemical
process is responsible?
A. Oxidative phosphorylation
B. Fermentation of pyruvate to lactate
C. Fatty acid synthesis
D. Glycogenolysis only
, Answer: B. Fermentation of pyruvate to lactate
Rationale: Under low oxygen conditions, NADH cannot be re-oxidized by the ETC.
Pyruvate is reduced to lactate by lactate dehydrogenase, regenerating NAD+ so
glycolysis can continue.
7. Which of the following is the correct definition of a "catabolic" pathway?
A. The synthesis of complex molecules from simpler ones, requiring energy
B. The breakdown of complex molecules into simpler ones, releasing energy
C. The storage of glucose as glycogen in the liver
D. The flow of genetic information from DNA to protein
Answer: B. The breakdown of complex molecules into simpler ones, releasing
energy
Rationale: Catabolism is the destructive phase of metabolism, breaking down
macromolecules to release energy (e.g., cellular respiration).
8. A scientist uses the term flux regarding a biochemical pathway. What does flux
mean?
A. The number of enzymes in the pathway
B. The rate of flow of molecules through a biochemical pathway
C. The net change in free energy of the pathway
Section 1: Core Concepts & Energetics (Questions 1-30)
1. A researcher measures enzyme activity at increasing substrate concentrations
and notices the reaction rate eventually plateaus. What BEST explains this
observation?
A. Substrate inhibition
B. Enzyme saturation at maximum velocity
C. Protein denaturation
D. Competitive inhibition
Answer: B. Enzyme saturation at maximum velocity
Rationale: At high substrate concentrations, all active sites of the enzyme become
occupied, reaching a maximum velocity (Vmax).
2. What is the sign (+ or -) of ΔG for the breakdown of ATP to ADP? Why is this
significant?
A. (+) Positive; it requires energy input
B. (-) Negative; it is spontaneous and can power other cellular processes
C. (+) Positive; it stores energy for later use
D. (-) Negative; it indicates the reaction is at equilibrium
,Answer: B. (-) Negative; it is spontaneous and can power other processes
Rationale: A negative ΔG indicates an exergonic (spontaneous) reaction, meaning
energy is released. This released energy is harnessed by the cell to drive
endergonic (non-spontaneous) reactions.
3. Which metabolic pathway primarily generates ATP under strictly anaerobic
conditions?
A. Citric acid cycle
B. Electron transport chain
C. Glycolysis
D. Beta-oxidation
Answer: C. Glycolysis
*Rationale: Glycolysis does not require oxygen and produces a net gain of 2 ATP
via substrate-level phosphorylation.*
4. A deficiency in niacin (Vitamin B3) would most directly impair the production of
which molecule necessary for cellular respiration?
A. FADH2
B. NADH
C. Acetyl-CoA
,D. H2O
Answer: B. NADH
Rationale: Niacin is a precursor for NAD+ and NADP+. NAD+ is the oxidized form
that accepts electrons to become NADH, a crucial electron carrier.
5. Which statement best describes the role of oxygen in aerobic respiration?
A. It is the final electron acceptor in the electron transport chain
B. It directly phosphorylates ADP to form ATP
C. It is necessary for the reactions of glycolysis to proceed
D. It combines with carbon to form CO2 in the CAC
Answer: A. It is the final electron acceptor in the electron transport chain
Rationale: Oxygen has high electronegativity and accepts electrons at the end of
the ETC, combining with protons to form water. Without it, the ETC halts.
6. A patient has elevated blood lactate after intense exercise. What biochemical
process is responsible?
A. Oxidative phosphorylation
B. Fermentation of pyruvate to lactate
C. Fatty acid synthesis
D. Glycogenolysis only
, Answer: B. Fermentation of pyruvate to lactate
Rationale: Under low oxygen conditions, NADH cannot be re-oxidized by the ETC.
Pyruvate is reduced to lactate by lactate dehydrogenase, regenerating NAD+ so
glycolysis can continue.
7. Which of the following is the correct definition of a "catabolic" pathway?
A. The synthesis of complex molecules from simpler ones, requiring energy
B. The breakdown of complex molecules into simpler ones, releasing energy
C. The storage of glucose as glycogen in the liver
D. The flow of genetic information from DNA to protein
Answer: B. The breakdown of complex molecules into simpler ones, releasing
energy
Rationale: Catabolism is the destructive phase of metabolism, breaking down
macromolecules to release energy (e.g., cellular respiration).
8. A scientist uses the term flux regarding a biochemical pathway. What does flux
mean?
A. The number of enzymes in the pathway
B. The rate of flow of molecules through a biochemical pathway
C. The net change in free energy of the pathway
