WGU C785 BIOCHEMISTRY FINAL
EXAM 2026 QUESTIONS AND ANSWERS
1. Which level of protein structure is characterized by the formation of alpha-helices and
beta-pleated sheets through hydrogen bonding of the polypeptide backbone?
A. Primary structure
B. Quaternary structure
C. Tertiary structure
D. Secondary structure
Answer: D
Conceptual Explanation: Secondary structure refers to local folded structures that form
within a polypeptide due to interactions between atoms of the backbone (specifically
hydrogen bonds).
2. In the Michaelis-Menten model of enzyme kinetics, what does the Km represent?
A. The maximum velocity of the reaction
B. The enzyme concentration at half-saturation
C. The substrate concentration at which the reaction rate is half of Vmax
D. The rate constant of the total reaction
,Answer: C
Conceptual Explanation: Km, the Michaelis constant, is the substrate concentration at
which the reaction rate is 50% of the maximum velocity (Vmax). It reflects the affinity of
the enzyme for its substrate.
3. A mutation that results in the replacement of one amino acid with another is called a:
A. Silent mutation
B. Missense mutation
C. Nonsense mutation
D. Frameshift mutation
Answer: B
Conceptual Explanation: A missense mutation is a point mutation in which a single
nucleotide change results in a codon that codes for a different amino acid.
4. Which molecule acts as the final electron acceptor in the mitochondrial electron transport
chain?
A. NAD+
B. FAD
C. Water
D. Oxygen
Answer: D
, Conceptual Explanation: Molecular oxygen (O2) serves as the final electron acceptor at
Complex IV, where it is reduced to form water.
5. Which metabolic pathway is upregulated by glucagon in the liver during fasting?
A. Glycolysis
B. Gluconeogenesis
C. Fatty acid synthesis
D. Glycogenesis
Answer: B
Conceptual Explanation: Glucagon stimulates the liver to produce glucose through
gluconeogenesis and glycogenolysis to maintain blood sugar levels during fasting.
6. During DNA replication, which enzyme is responsible for unwinding the DNA double helix?
A. DNA Polymerase III
B. Primase
C. Ligase
D. Helicase
Answer: D
Conceptual Explanation: Helicase breaks the hydrogen bonds between nitrogenous bases
to unzip the double-stranded DNA molecule.
EXAM 2026 QUESTIONS AND ANSWERS
1. Which level of protein structure is characterized by the formation of alpha-helices and
beta-pleated sheets through hydrogen bonding of the polypeptide backbone?
A. Primary structure
B. Quaternary structure
C. Tertiary structure
D. Secondary structure
Answer: D
Conceptual Explanation: Secondary structure refers to local folded structures that form
within a polypeptide due to interactions between atoms of the backbone (specifically
hydrogen bonds).
2. In the Michaelis-Menten model of enzyme kinetics, what does the Km represent?
A. The maximum velocity of the reaction
B. The enzyme concentration at half-saturation
C. The substrate concentration at which the reaction rate is half of Vmax
D. The rate constant of the total reaction
,Answer: C
Conceptual Explanation: Km, the Michaelis constant, is the substrate concentration at
which the reaction rate is 50% of the maximum velocity (Vmax). It reflects the affinity of
the enzyme for its substrate.
3. A mutation that results in the replacement of one amino acid with another is called a:
A. Silent mutation
B. Missense mutation
C. Nonsense mutation
D. Frameshift mutation
Answer: B
Conceptual Explanation: A missense mutation is a point mutation in which a single
nucleotide change results in a codon that codes for a different amino acid.
4. Which molecule acts as the final electron acceptor in the mitochondrial electron transport
chain?
A. NAD+
B. FAD
C. Water
D. Oxygen
Answer: D
, Conceptual Explanation: Molecular oxygen (O2) serves as the final electron acceptor at
Complex IV, where it is reduced to form water.
5. Which metabolic pathway is upregulated by glucagon in the liver during fasting?
A. Glycolysis
B. Gluconeogenesis
C. Fatty acid synthesis
D. Glycogenesis
Answer: B
Conceptual Explanation: Glucagon stimulates the liver to produce glucose through
gluconeogenesis and glycogenolysis to maintain blood sugar levels during fasting.
6. During DNA replication, which enzyme is responsible for unwinding the DNA double helix?
A. DNA Polymerase III
B. Primase
C. Ligase
D. Helicase
Answer: D
Conceptual Explanation: Helicase breaks the hydrogen bonds between nitrogenous bases
to unzip the double-stranded DNA molecule.
