PORTAGE LEARNING
12/May/2026 — 9:32 AM
Module 2 Exam - Requires Respondus LockDown Browser + Webcam
Due No due date Points 100 Questions 40 Time Limit 120 Minutes Requires Respondus LockDown Browser
Instructions
Please read the following before beginning the exam:
You must TYPE your work for calculations or give an explanation for short answer questions in order to receive credit.
You may only use the methods and explanations provided by this course for your answers. The use of a method or
explanation that was not taught in this course is a violation of the Academic Integrity Policy.
You MUST only use the exam resource bank that is provided within the exam.
The use of printed versions of the exam resource bank will be considered a violation of the Academic Integrity Policy.
Any equation or constant used on an exam that is not from the exam resource bank and is different from the method
taught in this course will be considered an outside source and a violation of the Academic Integrity Policy.
During module exams you may not use any outside source of information such as the module, problem sets, notes,
Internet, tutor, etc.
The only items you are allowed to have in front of you are your computer, 1-2 pieces of blank scratch paper, a
calculator (non-cell phone), and a pen/pencil.
Your desk should be free of all other items and clutter.
Attempt History
Attempt Time Score
LATEST
Question 1 pts
Resource Bank
Scientific Calculator
A 56-year-old patient with diabetes presents with lactic acidosis after intense exercise. Blood tests reveal elevated lactate
and decreased pH. In your own words, explain the metabolic pathway that produces lactate under anaerobic conditions,
including the starting substrate, the enzyme involved, and why this pathway is necessary when oxygen is depleted.
Answer: Glycolysis breaks down glucose to pyruvate, producing 2 ATP and 2 NADH. Under anaerobic conditions,
pyruvate is reduced to lactate by lactate dehydrogenase, regenerating NAD+ from NADH. This regeneration is critical
because glycolysis requires NAD+ to continue producing ATP. Without oxygen, the electron transport chain cannot
reoxidize NADH, so fermentation provides the only mechanism to maintain NAD+ levels and sustain minimal ATP
production.
Correct!
Question 2 pts
,Question 2 pts
Resource Bank
Scientific Calculator
The region of an enzyme where the substrate binds and the chemical reaction occurs is called the __________.
Answer: Active site
Correct!
Question 3 pts
Resource Bank
Scientific Calculator
A patient is prescribed allopurinol for gout. Allopurinol is a competitive inhibitor of xanthine oxidase.
a) In your own words, explain how a competitive inhibitor affects enzyme kinetics, including what happens to Vmax and Km.
(2 pts)
b) Allopurinol is described as a "suicide inhibitor." Explain what this means at the molecular level and why this makes it
particularly effective for chronic gout management. (2 pts)
Answer:
a) Competitive inhibitors bind reversibly to the enzyme's active site, competing directly with the substrate. Vmax
remains unchanged because sufficiently high substrate concentrations can outcompete the inhibitor and saturate the
enzyme. However, Km increases because a higher substrate concentration is required to reach half of Vmax.
b) Suicide inhibitors (mechanism-based inhibitors) are converted by the enzyme's normal catalytic action into a reactive
intermediate that covalently binds to the enzyme, permanently inactivating it. This irreversible inhibition provides long-
lasting suppression of uric acid production, reducing the frequency of gout attacks with consistent dosing.
Correct!
Question 4 pts
Resource Bank
Scientific Calculator
Which of the following best describes the function of a cofactor?
a) It provides energy for the reaction
b) It is the primary substrate
c) It is a non-protein chemical compound that is required for the enzyme's activity
d) It inhibits enzyme function
Correct!
, Question 5 pts
Resource Bank
Scientific Calculator
Match the metabolic term to its definition:
Term Definition
Catabolism c) Breakdown of complex molecules into simpler ones, releasing energy
Anabolism a) Synthesis of complex molecules from simpler ones, requiring energy
Amphibolic pathway d) Pathway that has both catabolic and anabolic functions
Metabolism b) Sum of all chemical reactions in an organism
Answer: 1-c, 2-a, 3-d, 4-b
Correct!
Question 6 pts
Resource Bank
Scientific Calculator
True or False: The Michaelis constant (Km) represents the substrate concentration at which the reaction velocity is half of
Vmax, and a lower Km indicates higher enzyme affinity for the substrate.
True False
Correct!
Question 7 pts
Resource Bank
Scientific Calculator
A 42-year-old alcoholic patient presents with thiamine deficiency and lactic acidosis. Thiamine pyrophosphate (TPP) is a
cofactor for several enzymes in glucose metabolism.
a) Identify two metabolic enzymes that require TPP as a cofactor and describe their specific roles in metabolism. (2 pts)
b) Explain why thiamine deficiency leads to lactic acidosis, connecting your answer to the metabolic fate of pyruvate when
pyruvate dehydrogenase is impaired. (1 pt)
Answer:
a) Pyruvate dehydrogenase complex — catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA, linking
glycolysis to the citric acid cycle.
Transketolase — catalyzes the transfer of a two-carbon ketol group in the pentose phosphate pathway, generating
ribose and NADPH.
b) Without TPP, pyruvate dehydrogenase cannot convert pyruvate to acetyl-CoA. Pyruvate accumulates and is shunted
to lactate via lactate dehydrogenase to regenerate NAD+. The resulting lactate accumulation lowers blood pH, causing
12/May/2026 — 9:32 AM
Module 2 Exam - Requires Respondus LockDown Browser + Webcam
Due No due date Points 100 Questions 40 Time Limit 120 Minutes Requires Respondus LockDown Browser
Instructions
Please read the following before beginning the exam:
You must TYPE your work for calculations or give an explanation for short answer questions in order to receive credit.
You may only use the methods and explanations provided by this course for your answers. The use of a method or
explanation that was not taught in this course is a violation of the Academic Integrity Policy.
You MUST only use the exam resource bank that is provided within the exam.
The use of printed versions of the exam resource bank will be considered a violation of the Academic Integrity Policy.
Any equation or constant used on an exam that is not from the exam resource bank and is different from the method
taught in this course will be considered an outside source and a violation of the Academic Integrity Policy.
During module exams you may not use any outside source of information such as the module, problem sets, notes,
Internet, tutor, etc.
The only items you are allowed to have in front of you are your computer, 1-2 pieces of blank scratch paper, a
calculator (non-cell phone), and a pen/pencil.
Your desk should be free of all other items and clutter.
Attempt History
Attempt Time Score
LATEST
Question 1 pts
Resource Bank
Scientific Calculator
A 56-year-old patient with diabetes presents with lactic acidosis after intense exercise. Blood tests reveal elevated lactate
and decreased pH. In your own words, explain the metabolic pathway that produces lactate under anaerobic conditions,
including the starting substrate, the enzyme involved, and why this pathway is necessary when oxygen is depleted.
Answer: Glycolysis breaks down glucose to pyruvate, producing 2 ATP and 2 NADH. Under anaerobic conditions,
pyruvate is reduced to lactate by lactate dehydrogenase, regenerating NAD+ from NADH. This regeneration is critical
because glycolysis requires NAD+ to continue producing ATP. Without oxygen, the electron transport chain cannot
reoxidize NADH, so fermentation provides the only mechanism to maintain NAD+ levels and sustain minimal ATP
production.
Correct!
Question 2 pts
,Question 2 pts
Resource Bank
Scientific Calculator
The region of an enzyme where the substrate binds and the chemical reaction occurs is called the __________.
Answer: Active site
Correct!
Question 3 pts
Resource Bank
Scientific Calculator
A patient is prescribed allopurinol for gout. Allopurinol is a competitive inhibitor of xanthine oxidase.
a) In your own words, explain how a competitive inhibitor affects enzyme kinetics, including what happens to Vmax and Km.
(2 pts)
b) Allopurinol is described as a "suicide inhibitor." Explain what this means at the molecular level and why this makes it
particularly effective for chronic gout management. (2 pts)
Answer:
a) Competitive inhibitors bind reversibly to the enzyme's active site, competing directly with the substrate. Vmax
remains unchanged because sufficiently high substrate concentrations can outcompete the inhibitor and saturate the
enzyme. However, Km increases because a higher substrate concentration is required to reach half of Vmax.
b) Suicide inhibitors (mechanism-based inhibitors) are converted by the enzyme's normal catalytic action into a reactive
intermediate that covalently binds to the enzyme, permanently inactivating it. This irreversible inhibition provides long-
lasting suppression of uric acid production, reducing the frequency of gout attacks with consistent dosing.
Correct!
Question 4 pts
Resource Bank
Scientific Calculator
Which of the following best describes the function of a cofactor?
a) It provides energy for the reaction
b) It is the primary substrate
c) It is a non-protein chemical compound that is required for the enzyme's activity
d) It inhibits enzyme function
Correct!
, Question 5 pts
Resource Bank
Scientific Calculator
Match the metabolic term to its definition:
Term Definition
Catabolism c) Breakdown of complex molecules into simpler ones, releasing energy
Anabolism a) Synthesis of complex molecules from simpler ones, requiring energy
Amphibolic pathway d) Pathway that has both catabolic and anabolic functions
Metabolism b) Sum of all chemical reactions in an organism
Answer: 1-c, 2-a, 3-d, 4-b
Correct!
Question 6 pts
Resource Bank
Scientific Calculator
True or False: The Michaelis constant (Km) represents the substrate concentration at which the reaction velocity is half of
Vmax, and a lower Km indicates higher enzyme affinity for the substrate.
True False
Correct!
Question 7 pts
Resource Bank
Scientific Calculator
A 42-year-old alcoholic patient presents with thiamine deficiency and lactic acidosis. Thiamine pyrophosphate (TPP) is a
cofactor for several enzymes in glucose metabolism.
a) Identify two metabolic enzymes that require TPP as a cofactor and describe their specific roles in metabolism. (2 pts)
b) Explain why thiamine deficiency leads to lactic acidosis, connecting your answer to the metabolic fate of pyruvate when
pyruvate dehydrogenase is impaired. (1 pt)
Answer:
a) Pyruvate dehydrogenase complex — catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA, linking
glycolysis to the citric acid cycle.
Transketolase — catalyzes the transfer of a two-carbon ketol group in the pentose phosphate pathway, generating
ribose and NADPH.
b) Without TPP, pyruvate dehydrogenase cannot convert pyruvate to acetyl-CoA. Pyruvate accumulates and is shunted
to lactate via lactate dehydrogenase to regenerate NAD+. The resulting lactate accumulation lowers blood pH, causing
