JERSEY COLLEGE – MICROBIOLOGY
FINAL EXAM (2026) QUESTIONS AND
ANSWERS
1. Which component of the Gram-negative cell wall is responsible for its toxic properties
when the cell dies?
A. Peptidoglycan layer
B. Teichoic acids
C. Lipopolysaccharide (Lipid A)
D. Periplasmic space
Answer: C
Conceptual Explanation: Lipopolysaccharide (LPS), specifically the Lipid A portion, acts
as an endotoxin that triggers a strong immune response when released from the cell wall of
dying Gram-negative bacteria.
2. During which phase of the bacterial growth curve are cells most metabolically active and
sensitive to antibiotics like penicillin?
A. Log (Exponential) phase
,B. Stationary phase
C. Lag phase
D. Death phase
Answer: A
Conceptual Explanation: In the log phase, bacteria divide at a constant rate and are highly
active metabolically, making them most vulnerable to drugs that interfere with cell wall
synthesis.
3. An enzyme that catalyzes the unwinding of the DNA double helix during replication is:
A. DNA Polymerase III
B. Helicase
C. Primase
D. Ligase
Answer: B
Conceptual Explanation: Helicase is the enzyme responsible for breaking hydrogen bonds
between nitrogenous bases to unzip the DNA double helix.
4. Which of the following describes a bacterial cell that is ‘competent’?
A. It is capable of performing binary fission.
B. It is resistant to multiple antibiotics.
, C. It has the ability to form a pilus for conjugation.
D. It can take up naked DNA from the environment.
Answer: D
Conceptual Explanation: Competence refers to a cell’s physiological state that allows it to
take up exogenous DNA through the process of transformation.
5. Which metabolic pathway produces the highest net yield of ATP per molecule of glucose in
an aerobic environment?
A. Glycolysis
B. Fermentation
C. Electron Transport Chain and Chemiosmosis
D. The Krebs Cycle
Answer: C
Conceptual Explanation: The electron transport chain, coupled with chemiosmosis
(oxidative phosphorylation), produces approximately 34 ATP, far exceeding other
pathways.
6. Which type of mutation results in a premature stop codon and typically leads to a
nonfunctional protein?
A. Nonsense mutation
B. Silent mutation
FINAL EXAM (2026) QUESTIONS AND
ANSWERS
1. Which component of the Gram-negative cell wall is responsible for its toxic properties
when the cell dies?
A. Peptidoglycan layer
B. Teichoic acids
C. Lipopolysaccharide (Lipid A)
D. Periplasmic space
Answer: C
Conceptual Explanation: Lipopolysaccharide (LPS), specifically the Lipid A portion, acts
as an endotoxin that triggers a strong immune response when released from the cell wall of
dying Gram-negative bacteria.
2. During which phase of the bacterial growth curve are cells most metabolically active and
sensitive to antibiotics like penicillin?
A. Log (Exponential) phase
,B. Stationary phase
C. Lag phase
D. Death phase
Answer: A
Conceptual Explanation: In the log phase, bacteria divide at a constant rate and are highly
active metabolically, making them most vulnerable to drugs that interfere with cell wall
synthesis.
3. An enzyme that catalyzes the unwinding of the DNA double helix during replication is:
A. DNA Polymerase III
B. Helicase
C. Primase
D. Ligase
Answer: B
Conceptual Explanation: Helicase is the enzyme responsible for breaking hydrogen bonds
between nitrogenous bases to unzip the DNA double helix.
4. Which of the following describes a bacterial cell that is ‘competent’?
A. It is capable of performing binary fission.
B. It is resistant to multiple antibiotics.
, C. It has the ability to form a pilus for conjugation.
D. It can take up naked DNA from the environment.
Answer: D
Conceptual Explanation: Competence refers to a cell’s physiological state that allows it to
take up exogenous DNA through the process of transformation.
5. Which metabolic pathway produces the highest net yield of ATP per molecule of glucose in
an aerobic environment?
A. Glycolysis
B. Fermentation
C. Electron Transport Chain and Chemiosmosis
D. The Krebs Cycle
Answer: C
Conceptual Explanation: The electron transport chain, coupled with chemiosmosis
(oxidative phosphorylation), produces approximately 34 ATP, far exceeding other
pathways.
6. Which type of mutation results in a premature stop codon and typically leads to a
nonfunctional protein?
A. Nonsense mutation
B. Silent mutation
