WGU C785 BIOCHEMISTRY UNIT EXAM QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
Note: This document contains original practice questions aligned with standard biochemistry curriculum topics (enzymes, metabolism, lipids,
genetics, bioenergetics). These are not the actual confidential WGU exam questions. Use this for study and concept review only.
Core Domains
Enzyme Kinetics and Regulation
Carbohydrate Metabolism (Glycolysis, TCA, PPP)
Lipid Metabolism and Transport
Bioenergetics and Oxidative Phosphorylation
Protein Structure and Function
DNA/RNA Synthesis and Regulation
Introduction
This practice assessment is designed to reinforce foundational and applied biochemistry knowledge essential for professional success. It evaluates
understanding of metabolic pathways, enzymatic mechanisms, molecular genetics, and bioenergetic principles. The multiple-choice and scenario-
based format emphasizes critical thinking, real-world clinical application, and decision-making in biochemical contexts. Students will practice
interpreting data, predicting pathway outcomes, and applying regulatory concepts to complex biological systems.
Section One: Questions 1–100
1. Which of the following best describes the effect of a non-competitive inhibitor on enzyme kinetics?
A. Increases Km, no change in Vmax
B. No change in Km, decreases Vmax
C. Increases Km, increases Vmax
D. Decreases Km, decreases Vmax
,🟢 B. No change in Km, decreases Vmax
🔴 RATIONALE: Non-competitive inhibitors bind to an allosteric site, reducing the number of functional enzyme molecules (lowering Vmax)
without affecting substrate binding affinity (Km remains unchanged).
2. In glycolysis, which enzyme catalyzes the committed step that is highly regulated by ATP and citrate?
A. Hexokinase
B. Phosphofructokinase-1 (PFK-1)
C. Pyruvate kinase
D. Aldolase
🟢 B. Phosphofructokinase-1 (PFK-1)
🔴 RATIONALE: PFK-1 catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, the committed step of glycolysis. It is
inhibited by ATP and citrate (signaling high energy).
3. Which lipoprotein is primarily responsible for transporting exogenous triglycerides from the intestine to peripheral tissues?
A. HDL
B. LDL
C. VLDL
D. Chylomicrons
🟢 D. Chylomicrons
🔴 RATIONALE: Chylomicrons transport dietary (exogenous) triglycerides from the intestine. VLDL transports endogenous triglycerides from the
liver.
,4. During oxidative phosphorylation, which complex directly transfers electrons from FADH₂ to the electron transport chain?
A. Complex I
B. Complex II
C. Complex III
D. Complex IV
🟢 B. Complex II
🔴 RATIONALE: Complex II (succinate dehydrogenase) accepts electrons from FADH₂ (generated during succinate → fumarate) and transfers them
to ubiquinone.
5. Which amino acid is most likely to be found in the active site of an enzyme catalyzing a reaction involving proton transfer at
physiological pH?
A. Glycine
B. Histidine
C. Valine
D. Phenylalanine
🟢 B. Histidine
🔴 RATIONALE: Histidine has a pKa near 6.0, allowing it to act as both a proton donor and acceptor at physiological pH, making it ideal for acid-
base catalysis.
6. In the Cori cycle, lactate produced in muscle is converted to glucose in which organ?
A. Kidney
B. Liver
C. Heart
D. Brain
🟢 B. Liver
, 🔴 RATIONALE: The Cori cycle involves lactate transport from muscle to the liver, where gluconeogenesis converts lactate back to glucose.
7. Which of the following is a key regulatory enzyme in fatty acid synthesis?
A. Acetyl-CoA carboxylase
B. HMG-CoA reductase
C. Carnitine acyltransferase
D. Fatty acid synthase
🟢 A. Acetyl-CoA carboxylase
🔴 RATIONALE: Acetyl-CoA carboxylase converts acetyl-CoA to malonyl-CoA and is the primary regulated step in fatty acid synthesis (activated by
insulin, inhibited by epinephrine).
8. What is the primary function of the pentose phosphate pathway?
A. Generate ATP
B. Produce NADPH and ribose-5-phosphate
C. Break down glucose for energy
D. Synthesize fatty acids
🟢 B. Produce NADPH and ribose-5-phosphate
🔴 RATIONALE: The PPP generates NADPH (for reductive biosynthesis and antioxidant defense) and ribose-5-phosphate (for nucleotide synthesis).
9. Which mutation type is most likely to result in a frameshift?
A. Substitution
B. Insertion of 1 nucleotide
C. Deletion of 3 nucleotides
D. Silent mutation
2026 Q&A | INSTANT DOWNLOAD PDF
Note: This document contains original practice questions aligned with standard biochemistry curriculum topics (enzymes, metabolism, lipids,
genetics, bioenergetics). These are not the actual confidential WGU exam questions. Use this for study and concept review only.
Core Domains
Enzyme Kinetics and Regulation
Carbohydrate Metabolism (Glycolysis, TCA, PPP)
Lipid Metabolism and Transport
Bioenergetics and Oxidative Phosphorylation
Protein Structure and Function
DNA/RNA Synthesis and Regulation
Introduction
This practice assessment is designed to reinforce foundational and applied biochemistry knowledge essential for professional success. It evaluates
understanding of metabolic pathways, enzymatic mechanisms, molecular genetics, and bioenergetic principles. The multiple-choice and scenario-
based format emphasizes critical thinking, real-world clinical application, and decision-making in biochemical contexts. Students will practice
interpreting data, predicting pathway outcomes, and applying regulatory concepts to complex biological systems.
Section One: Questions 1–100
1. Which of the following best describes the effect of a non-competitive inhibitor on enzyme kinetics?
A. Increases Km, no change in Vmax
B. No change in Km, decreases Vmax
C. Increases Km, increases Vmax
D. Decreases Km, decreases Vmax
,🟢 B. No change in Km, decreases Vmax
🔴 RATIONALE: Non-competitive inhibitors bind to an allosteric site, reducing the number of functional enzyme molecules (lowering Vmax)
without affecting substrate binding affinity (Km remains unchanged).
2. In glycolysis, which enzyme catalyzes the committed step that is highly regulated by ATP and citrate?
A. Hexokinase
B. Phosphofructokinase-1 (PFK-1)
C. Pyruvate kinase
D. Aldolase
🟢 B. Phosphofructokinase-1 (PFK-1)
🔴 RATIONALE: PFK-1 catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, the committed step of glycolysis. It is
inhibited by ATP and citrate (signaling high energy).
3. Which lipoprotein is primarily responsible for transporting exogenous triglycerides from the intestine to peripheral tissues?
A. HDL
B. LDL
C. VLDL
D. Chylomicrons
🟢 D. Chylomicrons
🔴 RATIONALE: Chylomicrons transport dietary (exogenous) triglycerides from the intestine. VLDL transports endogenous triglycerides from the
liver.
,4. During oxidative phosphorylation, which complex directly transfers electrons from FADH₂ to the electron transport chain?
A. Complex I
B. Complex II
C. Complex III
D. Complex IV
🟢 B. Complex II
🔴 RATIONALE: Complex II (succinate dehydrogenase) accepts electrons from FADH₂ (generated during succinate → fumarate) and transfers them
to ubiquinone.
5. Which amino acid is most likely to be found in the active site of an enzyme catalyzing a reaction involving proton transfer at
physiological pH?
A. Glycine
B. Histidine
C. Valine
D. Phenylalanine
🟢 B. Histidine
🔴 RATIONALE: Histidine has a pKa near 6.0, allowing it to act as both a proton donor and acceptor at physiological pH, making it ideal for acid-
base catalysis.
6. In the Cori cycle, lactate produced in muscle is converted to glucose in which organ?
A. Kidney
B. Liver
C. Heart
D. Brain
🟢 B. Liver
, 🔴 RATIONALE: The Cori cycle involves lactate transport from muscle to the liver, where gluconeogenesis converts lactate back to glucose.
7. Which of the following is a key regulatory enzyme in fatty acid synthesis?
A. Acetyl-CoA carboxylase
B. HMG-CoA reductase
C. Carnitine acyltransferase
D. Fatty acid synthase
🟢 A. Acetyl-CoA carboxylase
🔴 RATIONALE: Acetyl-CoA carboxylase converts acetyl-CoA to malonyl-CoA and is the primary regulated step in fatty acid synthesis (activated by
insulin, inhibited by epinephrine).
8. What is the primary function of the pentose phosphate pathway?
A. Generate ATP
B. Produce NADPH and ribose-5-phosphate
C. Break down glucose for energy
D. Synthesize fatty acids
🟢 B. Produce NADPH and ribose-5-phosphate
🔴 RATIONALE: The PPP generates NADPH (for reductive biosynthesis and antioxidant defense) and ribose-5-phosphate (for nucleotide synthesis).
9. Which mutation type is most likely to result in a frameshift?
A. Substitution
B. Insertion of 1 nucleotide
C. Deletion of 3 nucleotides
D. Silent mutation
