CHEM 210 BIOCHEMISTRY MODULE 4 EXAM 2026/2027
UPDATE | Geneva College / Portage Learning | Verified
Questions & Revised Answers | Pass Guaranteed - A+
Graded
Time Allowed: 90 minutes
Total Points: 100
SECTION A: MULTIPLE CHOICE
(15 questions, 3 points each = 45 points total)
Instructions: Select the best answer for each question. Each question has exactly one
correct answer.
Q1. Which monosaccharide is the primary fuel for the brain under normal physiological
conditions?
A. Fructose
B. Galactose
C. Glucose. [CORRECT]
D. Mannose
Correct Answer: C
Rationale: Glucose is the primary and preferred fuel for the brain under normal
conditions. The brain consumes approximately 120 grams of glucose daily, representing
,about 60% of the body's glucose utilization at rest. While the brain can adapt to use
ketone bodies during prolonged fasting or starvation, glucose remains essential for
optimal neurological function. Fructose (A) is primarily metabolized by the liver and
cannot efficiently cross the blood-brain barrier. Galactose (B) must be converted to
glucose-1-phosphate via the Leloir pathway before systemic utilization. Mannose (D) is
a C-2 epimer of glucose but is not a significant energy source for neural tissue.
Q2. In the glycolytic pathway, which enzyme catalyzes the first committed step and is
the primary regulatory point?
A. Hexokinase
B. Phosphofructokinase-1 (PFK-1). [CORRECT]
C. Pyruvate kinase
D. Glyceraldehyde-3-phosphate dehydrogenase
Correct Answer: B
Rationale: Phosphofructokinase-1 (PFK-1) catalyzes the phosphorylation of
fructose-6-phosphate to fructose-1,6-bisphosphate, representing the first irreversible,
committed step of glycolysis. This reaction is highly exergonic (ΔG°' = -14.2 kJ/mol) and
subject to complex allosteric regulation: activated by AMP and
fructose-2,6-bisphosphate (F2,6BP), inhibited by ATP and citrate. While hexokinase (A)
catalyzes the first step, it is not the committed step (glucose-6-phosphate can enter
glycogen synthesis or PPP). Pyruvate kinase (C) is an important regulatory enzyme but
controls the final step. Glyceraldehyde-3-phosphate dehydrogenase (D) is not a major
regulatory point.
, Q3. A patient with Type 1 Diabetes Mellitus presents with fasting hyperglycemia (320
mg/dL) and glycosuria. Which metabolic consequence results from the absence of
functional insulin signaling?
A. Decreased hepatic gluconeogenesis
B. Increased hepatic gluconeogenesis and decreased peripheral glucose uptake.
[CORRECT]
C. Increased glycogen synthesis in liver and muscle
D. Decreased lipolysis in adipose tissue
Correct Answer: B
Rationale: In Type 1 DM, absolute insulin deficiency leads to: (1) unrestrained hepatic
gluconeogenesis (insulin normally suppresses via decreased FOXO1 activity and
reduced enzyme expression), and (2) failed GLUT4 translocation in muscle/adipose
tissue, preventing glucose uptake. This creates the "starvation in the midst of plenty"
paradox—hyperglycemia with cellular glucose deprivation. Option A is incorrect
(gluconeogenesis increases, not decreases). Option C is incorrect (glycogenolysis
predominates; glycogen synthesis requires active glycogen synthase via
insulin-dependent dephosphorylation). Option D is incorrect (lipolysis increases
dramatically due to uninhibited hormone-sensitive lipase).
Q4. Which intermediate of the pentose phosphate pathway (PPP) provides the carbon
skeleton for nucleotide biosynthesis?
A. Glucose-6-phosphate
B. Ribose-5-phosphate. [CORRECT]
UPDATE | Geneva College / Portage Learning | Verified
Questions & Revised Answers | Pass Guaranteed - A+
Graded
Time Allowed: 90 minutes
Total Points: 100
SECTION A: MULTIPLE CHOICE
(15 questions, 3 points each = 45 points total)
Instructions: Select the best answer for each question. Each question has exactly one
correct answer.
Q1. Which monosaccharide is the primary fuel for the brain under normal physiological
conditions?
A. Fructose
B. Galactose
C. Glucose. [CORRECT]
D. Mannose
Correct Answer: C
Rationale: Glucose is the primary and preferred fuel for the brain under normal
conditions. The brain consumes approximately 120 grams of glucose daily, representing
,about 60% of the body's glucose utilization at rest. While the brain can adapt to use
ketone bodies during prolonged fasting or starvation, glucose remains essential for
optimal neurological function. Fructose (A) is primarily metabolized by the liver and
cannot efficiently cross the blood-brain barrier. Galactose (B) must be converted to
glucose-1-phosphate via the Leloir pathway before systemic utilization. Mannose (D) is
a C-2 epimer of glucose but is not a significant energy source for neural tissue.
Q2. In the glycolytic pathway, which enzyme catalyzes the first committed step and is
the primary regulatory point?
A. Hexokinase
B. Phosphofructokinase-1 (PFK-1). [CORRECT]
C. Pyruvate kinase
D. Glyceraldehyde-3-phosphate dehydrogenase
Correct Answer: B
Rationale: Phosphofructokinase-1 (PFK-1) catalyzes the phosphorylation of
fructose-6-phosphate to fructose-1,6-bisphosphate, representing the first irreversible,
committed step of glycolysis. This reaction is highly exergonic (ΔG°' = -14.2 kJ/mol) and
subject to complex allosteric regulation: activated by AMP and
fructose-2,6-bisphosphate (F2,6BP), inhibited by ATP and citrate. While hexokinase (A)
catalyzes the first step, it is not the committed step (glucose-6-phosphate can enter
glycogen synthesis or PPP). Pyruvate kinase (C) is an important regulatory enzyme but
controls the final step. Glyceraldehyde-3-phosphate dehydrogenase (D) is not a major
regulatory point.
, Q3. A patient with Type 1 Diabetes Mellitus presents with fasting hyperglycemia (320
mg/dL) and glycosuria. Which metabolic consequence results from the absence of
functional insulin signaling?
A. Decreased hepatic gluconeogenesis
B. Increased hepatic gluconeogenesis and decreased peripheral glucose uptake.
[CORRECT]
C. Increased glycogen synthesis in liver and muscle
D. Decreased lipolysis in adipose tissue
Correct Answer: B
Rationale: In Type 1 DM, absolute insulin deficiency leads to: (1) unrestrained hepatic
gluconeogenesis (insulin normally suppresses via decreased FOXO1 activity and
reduced enzyme expression), and (2) failed GLUT4 translocation in muscle/adipose
tissue, preventing glucose uptake. This creates the "starvation in the midst of plenty"
paradox—hyperglycemia with cellular glucose deprivation. Option A is incorrect
(gluconeogenesis increases, not decreases). Option C is incorrect (glycogenolysis
predominates; glycogen synthesis requires active glycogen synthase via
insulin-dependent dephosphorylation). Option D is incorrect (lipolysis increases
dramatically due to uninhibited hormone-sensitive lipase).
Q4. Which intermediate of the pentose phosphate pathway (PPP) provides the carbon
skeleton for nucleotide biosynthesis?
A. Glucose-6-phosphate
B. Ribose-5-phosphate. [CORRECT]
