C785 Biochemistry Midterm Comprehensive Review 2026 |WGU
1. Which bond is responsible for the primary structure of a protein?
A. Hydrogen bonds
B. Ionic bonds
C. Peptide bonds
D. Disulfide bridges
Answer: C
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
2. What happens to the oxygen-binding affinity of hemoglobin when the pH
decreases?
A. Affinity increases
B. Affinity remains unchanged
C. Affinity decreases
D. Hemoglobin denatures immediately
Answer: C
Rationale: According to the Bohr effect, a decrease in pH (increase in H+) stabilizes the T-
state, decreasing oxygen affinity.
,3. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Helicase
C. Ligase
D. Primase
Answer: B
Rationale: Helicase breaks the hydrogen bonds between base pairs to unwind the DNA
strands.
4. In competitive inhibition, how are Vmax and Km affected?
A. Vmax decreases, Km increases
B. Vmax stays the same, Km increases
C. Vmax decreases, Km stays the same
D. Both Vmax and Km decrease
Answer: B
Rationale: Competitive inhibitors compete for the active site, increasing the amount of
substrate needed to reach half Vmax (increasing Km), but Vmax can still be reached with
enough substrate.
5. Which part of the amino acid defines its chemical properties and identity?
A. The R-group (side chain)
B. The Carboxyl group
C. The Amino group
D. The Alpha carbon
Answer: A
Rationale: The R-group or side chain varies between the 20 amino acids and determines
their chemical behavior.
, 6. What is the net ATP yield of glycolysis per molecule of glucose?
A. 1 ATP
B. 2 ATP
C. 4 ATP
D. 36 ATP
Answer: B
Rationale: Glycolysis produces 4 ATP but consumes 2 ATP in the investment phase,
resulting in a net gain of 2 ATP.
7. Which molecule acts as the final electron acceptor in the Electron Transport
Chain?
A. Oxygen
B. Carbon dioxide
C. Water
D. NADH
Answer: A
Rationale: Oxygen accepts electrons at the end of the ETC to form water.
8. Which level of protein structure involves alpha-helices and beta-pleated
sheets?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: B
Rationale: Secondary structure refers to local folding patterns stabilized by hydrogen
bonds between backbone atoms.
1. Which bond is responsible for the primary structure of a protein?
A. Hydrogen bonds
B. Ionic bonds
C. Peptide bonds
D. Disulfide bridges
Answer: C
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
2. What happens to the oxygen-binding affinity of hemoglobin when the pH
decreases?
A. Affinity increases
B. Affinity remains unchanged
C. Affinity decreases
D. Hemoglobin denatures immediately
Answer: C
Rationale: According to the Bohr effect, a decrease in pH (increase in H+) stabilizes the T-
state, decreasing oxygen affinity.
,3. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Helicase
C. Ligase
D. Primase
Answer: B
Rationale: Helicase breaks the hydrogen bonds between base pairs to unwind the DNA
strands.
4. In competitive inhibition, how are Vmax and Km affected?
A. Vmax decreases, Km increases
B. Vmax stays the same, Km increases
C. Vmax decreases, Km stays the same
D. Both Vmax and Km decrease
Answer: B
Rationale: Competitive inhibitors compete for the active site, increasing the amount of
substrate needed to reach half Vmax (increasing Km), but Vmax can still be reached with
enough substrate.
5. Which part of the amino acid defines its chemical properties and identity?
A. The R-group (side chain)
B. The Carboxyl group
C. The Amino group
D. The Alpha carbon
Answer: A
Rationale: The R-group or side chain varies between the 20 amino acids and determines
their chemical behavior.
, 6. What is the net ATP yield of glycolysis per molecule of glucose?
A. 1 ATP
B. 2 ATP
C. 4 ATP
D. 36 ATP
Answer: B
Rationale: Glycolysis produces 4 ATP but consumes 2 ATP in the investment phase,
resulting in a net gain of 2 ATP.
7. Which molecule acts as the final electron acceptor in the Electron Transport
Chain?
A. Oxygen
B. Carbon dioxide
C. Water
D. NADH
Answer: A
Rationale: Oxygen accepts electrons at the end of the ETC to form water.
8. Which level of protein structure involves alpha-helices and beta-pleated
sheets?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: B
Rationale: Secondary structure refers to local folding patterns stabilized by hydrogen
bonds between backbone atoms.
