C785 Biochemistry Final Exam Comprehensive Review / ? WGU
UPDATED ACTUAL Questions and CORRECT Answers
1. Which level of protein structure is characterized by the sequence of amino
acids linked by peptide bonds?
A. Secondary structure
B. Quaternary structure
C. Tertiary structure
D. Primary structure
Answer: D
Rationale: Primary structure is the linear sequence of amino acids in a polypeptide chain.
2. What happens to the Km of an enzyme in the presence of a competitive
inhibitor?
A. Km decreases
B. Km stays the same
C. Km increases
D. Km becomes zero
Answer: C
Rationale: Competitive inhibitors compete with the substrate for the active site, effectively
increasing the amount of substrate needed to reach half-maximal velocity (Km).
,3. Which molecule acts as the primary buffer in the human blood to maintain
pH?
A. Phosphate buffer
B. Bicarbonate buffer system
C. Acetate buffer
D. Ammonia buffer
Answer: B
Rationale: The bicarbonate buffer system (CO2/HCO3-) is the most important
extracellular buffer for maintaining blood pH.
4. Hemoglobin’s affinity for oxygen decreases when which of the following
increases?
A. pH
B. Oxygen concentration
C. 2,3-Bisphosphoglycerate (2,3-BPG)
D. Carbon monoxide concentration
Answer: C
Rationale: Increased 2,3-BPG stabilizes the T-state (tense state) of hemoglobin, reducing
its affinity for oxygen and promoting oxygen release to tissues.
5. Which process converts glucose into two molecules of pyruvate?
A. Gluconeogenesis
B. Glycogenolysis
C. Glycolysis
D. Citric Acid Cycle
Answer: C
Rationale: Glycolysis is the metabolic pathway that breaks down glucose into pyruvate,
producing a net of 2 ATP and 2 NADH.
, 6. In the Electron Transport Chain, which complex is responsible for transferring
electrons to Oxygen?
A. Complex I
B. Complex II
C. Complex IV
D. Complex III
Answer: C
Rationale: Complex IV (Cytochrome c oxidase) transfers electrons to oxygen, which is the
final electron acceptor, forming water.
7. Which enzyme is the rate-limiting step of glycolysis?
A. Phosphofructokinase-1 (PFK-1)
B. Hexokinase
C. Pyruvate Kinase
D. Aldolase
Answer: A
Rationale: PFK-1 is the primary regulatory and rate-limiting enzyme of glycolysis,
inhibited by ATP and citrate.
8. What is the net ATP yield from one molecule of glucose during anaerobic
fermentation in muscle cells?
A. 4 ATP
B. 2 ATP
C. 32 ATP
D. 36 ATP
Answer: B
Rationale: Anaerobic glycolysis yields only the 2 net ATP produced during the glycolysis
phase, as oxidative phosphorylation does not occur.
UPDATED ACTUAL Questions and CORRECT Answers
1. Which level of protein structure is characterized by the sequence of amino
acids linked by peptide bonds?
A. Secondary structure
B. Quaternary structure
C. Tertiary structure
D. Primary structure
Answer: D
Rationale: Primary structure is the linear sequence of amino acids in a polypeptide chain.
2. What happens to the Km of an enzyme in the presence of a competitive
inhibitor?
A. Km decreases
B. Km stays the same
C. Km increases
D. Km becomes zero
Answer: C
Rationale: Competitive inhibitors compete with the substrate for the active site, effectively
increasing the amount of substrate needed to reach half-maximal velocity (Km).
,3. Which molecule acts as the primary buffer in the human blood to maintain
pH?
A. Phosphate buffer
B. Bicarbonate buffer system
C. Acetate buffer
D. Ammonia buffer
Answer: B
Rationale: The bicarbonate buffer system (CO2/HCO3-) is the most important
extracellular buffer for maintaining blood pH.
4. Hemoglobin’s affinity for oxygen decreases when which of the following
increases?
A. pH
B. Oxygen concentration
C. 2,3-Bisphosphoglycerate (2,3-BPG)
D. Carbon monoxide concentration
Answer: C
Rationale: Increased 2,3-BPG stabilizes the T-state (tense state) of hemoglobin, reducing
its affinity for oxygen and promoting oxygen release to tissues.
5. Which process converts glucose into two molecules of pyruvate?
A. Gluconeogenesis
B. Glycogenolysis
C. Glycolysis
D. Citric Acid Cycle
Answer: C
Rationale: Glycolysis is the metabolic pathway that breaks down glucose into pyruvate,
producing a net of 2 ATP and 2 NADH.
, 6. In the Electron Transport Chain, which complex is responsible for transferring
electrons to Oxygen?
A. Complex I
B. Complex II
C. Complex IV
D. Complex III
Answer: C
Rationale: Complex IV (Cytochrome c oxidase) transfers electrons to oxygen, which is the
final electron acceptor, forming water.
7. Which enzyme is the rate-limiting step of glycolysis?
A. Phosphofructokinase-1 (PFK-1)
B. Hexokinase
C. Pyruvate Kinase
D. Aldolase
Answer: A
Rationale: PFK-1 is the primary regulatory and rate-limiting enzyme of glycolysis,
inhibited by ATP and citrate.
8. What is the net ATP yield from one molecule of glucose during anaerobic
fermentation in muscle cells?
A. 4 ATP
B. 2 ATP
C. 32 ATP
D. 36 ATP
Answer: B
Rationale: Anaerobic glycolysis yields only the 2 net ATP produced during the glycolysis
phase, as oxidative phosphorylation does not occur.
