WGU C785 BIOCHEMISTRY FINAL
EXAM PREP QUESTIONS AND
ANSWERS
1. In the bicarbonate buffer system, how does the body respond to a decrease in blood pH
(acidosis)?
A. The lungs increase the rate of CO2 exhalation through hyperventilation.
B. The kidneys decrease the excretion of bicarbonate ions.
C. The blood increases the concentration of carbonic acid.
D. The body decreases the respiratory rate to retain H+ ions.
Answer: A
Conceptual Explanation: To combat acidosis (excess H+), the body shifts the equilibrium
of the bicarbonate buffer system toward CO2 and water. Hyperventilation removes CO2,
effectively lowering the H+ concentration and raising the pH back to normal.
2. Which level of protein structure is characterized by the sequence of amino acids linked by
peptide bonds?
A. Quaternary structure
,B. Secondary structure
C. Tertiary structure
D. Primary structure
Answer: D
Conceptual Explanation: Primary structure refers to the linear sequence of amino acids
held together by covalent peptide bonds.
3. Which amino acid substitution is responsible for the formation of hemoglobin S in Sickle
Cell Anemia?
A. Valine is replaced by Glutamate
B. Glutamate is replaced by Valine
C. Lysine is replaced by Arginine
D. Glycine is replaced by Alanine
Answer: B
Conceptual Explanation: Sickle cell anemia involves a missense mutation where the
hydrophilic glutamate (charged) is replaced by the hydrophobic valine (non-polar) at
position 6 of the beta-globin chain.
4. What effect does a competitive inhibitor have on the kinetics of an enzyme-catalyzed
reaction?
A. It increases Vmax and decreases Km.
, B. It leaves Vmax unchanged and increases Km.
C. It decreases Vmax and leaves Km unchanged.
D. It decreases both Vmax and Km.
Answer: B
Conceptual Explanation: Competitive inhibitors compete with the substrate for the active
site. They can be overcome by high substrate concentrations (Vmax stays same), but they
make the enzyme appear to have a lower affinity for the substrate (Km increases).
5. Which of the following describes the ‘Bohr Effect’ regarding hemoglobin?
A. Low pH (high H+) and high CO2 decrease hemoglobin’s affinity for oxygen.
B. High pH increases hemoglobin’s affinity for oxygen.
C. Increased 2,3-BPG increases hemoglobin’s affinity for oxygen.
D. Low CO2 levels shift the oxygen dissociation curve to the right.
Answer: A
Conceptual Explanation: The Bohr Effect describes how CO2 and H+ (low pH) stabilize
the T-state (tense state) of hemoglobin, causing it to release oxygen more readily in
metabolically active tissues.
6. What is the primary function of the Pentose Phosphate Pathway?
A. To generate NADPH and five-carbon sugars like ribose-5-phosphate.
B. To synthesize glycogen for energy storage.
EXAM PREP QUESTIONS AND
ANSWERS
1. In the bicarbonate buffer system, how does the body respond to a decrease in blood pH
(acidosis)?
A. The lungs increase the rate of CO2 exhalation through hyperventilation.
B. The kidneys decrease the excretion of bicarbonate ions.
C. The blood increases the concentration of carbonic acid.
D. The body decreases the respiratory rate to retain H+ ions.
Answer: A
Conceptual Explanation: To combat acidosis (excess H+), the body shifts the equilibrium
of the bicarbonate buffer system toward CO2 and water. Hyperventilation removes CO2,
effectively lowering the H+ concentration and raising the pH back to normal.
2. Which level of protein structure is characterized by the sequence of amino acids linked by
peptide bonds?
A. Quaternary structure
,B. Secondary structure
C. Tertiary structure
D. Primary structure
Answer: D
Conceptual Explanation: Primary structure refers to the linear sequence of amino acids
held together by covalent peptide bonds.
3. Which amino acid substitution is responsible for the formation of hemoglobin S in Sickle
Cell Anemia?
A. Valine is replaced by Glutamate
B. Glutamate is replaced by Valine
C. Lysine is replaced by Arginine
D. Glycine is replaced by Alanine
Answer: B
Conceptual Explanation: Sickle cell anemia involves a missense mutation where the
hydrophilic glutamate (charged) is replaced by the hydrophobic valine (non-polar) at
position 6 of the beta-globin chain.
4. What effect does a competitive inhibitor have on the kinetics of an enzyme-catalyzed
reaction?
A. It increases Vmax and decreases Km.
, B. It leaves Vmax unchanged and increases Km.
C. It decreases Vmax and leaves Km unchanged.
D. It decreases both Vmax and Km.
Answer: B
Conceptual Explanation: Competitive inhibitors compete with the substrate for the active
site. They can be overcome by high substrate concentrations (Vmax stays same), but they
make the enzyme appear to have a lower affinity for the substrate (Km increases).
5. Which of the following describes the ‘Bohr Effect’ regarding hemoglobin?
A. Low pH (high H+) and high CO2 decrease hemoglobin’s affinity for oxygen.
B. High pH increases hemoglobin’s affinity for oxygen.
C. Increased 2,3-BPG increases hemoglobin’s affinity for oxygen.
D. Low CO2 levels shift the oxygen dissociation curve to the right.
Answer: A
Conceptual Explanation: The Bohr Effect describes how CO2 and H+ (low pH) stabilize
the T-state (tense state) of hemoglobin, causing it to release oxygen more readily in
metabolically active tissues.
6. What is the primary function of the Pentose Phosphate Pathway?
A. To generate NADPH and five-carbon sugars like ribose-5-phosphate.
B. To synthesize glycogen for energy storage.
