BIO 171 BASIC MICROBIOLOGY
ADVANCED PRACTICE EXAM
1. Which component is uniquely present in the cell walls of Gram-positive bacteria and
functions in cation transport and cell wall stability?
A. Teichoic acids
B. Lipopolysaccharide
C. Porin proteins
D. Periplasmic space
Answer: A
Conceptual Explanation: Teichoic acids are found in the thick peptidoglycan layer of
Gram-positive bacteria, providing structural integrity and acting as a conduit for ions.
2. Which of the following molecules is responsible for the heat resistance of bacterial
endospores?
A. Peptidoglycan
B. Dipicolinic acid
C. Ergosterol
D. Mycolic acid
,Answer: B
Conceptual Explanation: Dipicolinic acid complexed with calcium ions helps dehydrate
the endospore core, conferring high heat and chemical resistance.
3. In the process of oxidative phosphorylation, what is the immediate source of energy used
to synthesize ATP?
A. The proton motive force across the membrane
B. The flow of electrons through the ETC
C. The oxidation of NADH and FADH2
D. The reduction of oxygen to water
Answer: A
Conceptual Explanation: ATP synthase utilizes the potential energy of the electrochemical
gradient (proton motive force) to catalyze the phosphorylation of ADP to ATP.
4. Which enzyme is responsible for synthesizing a short RNA sequence to provide a 3’-OH
group for DNA polymerase III during replication?
A. Helicase
B. Primase
C. Gyrase
D. Ligase
Answer: B
, Conceptual Explanation: Primase is a type of RNA polymerase that creates an RNA primer
necessary for DNA polymerase to begin synthesis.
5. A bacterium that uses light for energy and organic compounds as its carbon source is
classified as a:
A. Photoheterotroph
B. Chemoheterotroph
C. Photoautotroph
D. Chemoautotroph
Answer: A
Conceptual Explanation: Photoheterotrophs use light for ATP production but cannot fix
carbon dioxide, relying on organic molecules instead.
6. Which of the following horizontal gene transfer mechanisms involves the uptake of ‘naked’
DNA from the environment?
A. Transformation
B. Transduction
C. Conjugation
D. Transposition
Answer: A
ADVANCED PRACTICE EXAM
1. Which component is uniquely present in the cell walls of Gram-positive bacteria and
functions in cation transport and cell wall stability?
A. Teichoic acids
B. Lipopolysaccharide
C. Porin proteins
D. Periplasmic space
Answer: A
Conceptual Explanation: Teichoic acids are found in the thick peptidoglycan layer of
Gram-positive bacteria, providing structural integrity and acting as a conduit for ions.
2. Which of the following molecules is responsible for the heat resistance of bacterial
endospores?
A. Peptidoglycan
B. Dipicolinic acid
C. Ergosterol
D. Mycolic acid
,Answer: B
Conceptual Explanation: Dipicolinic acid complexed with calcium ions helps dehydrate
the endospore core, conferring high heat and chemical resistance.
3. In the process of oxidative phosphorylation, what is the immediate source of energy used
to synthesize ATP?
A. The proton motive force across the membrane
B. The flow of electrons through the ETC
C. The oxidation of NADH and FADH2
D. The reduction of oxygen to water
Answer: A
Conceptual Explanation: ATP synthase utilizes the potential energy of the electrochemical
gradient (proton motive force) to catalyze the phosphorylation of ADP to ATP.
4. Which enzyme is responsible for synthesizing a short RNA sequence to provide a 3’-OH
group for DNA polymerase III during replication?
A. Helicase
B. Primase
C. Gyrase
D. Ligase
Answer: B
, Conceptual Explanation: Primase is a type of RNA polymerase that creates an RNA primer
necessary for DNA polymerase to begin synthesis.
5. A bacterium that uses light for energy and organic compounds as its carbon source is
classified as a:
A. Photoheterotroph
B. Chemoheterotroph
C. Photoautotroph
D. Chemoautotroph
Answer: A
Conceptual Explanation: Photoheterotrophs use light for ATP production but cannot fix
carbon dioxide, relying on organic molecules instead.
6. Which of the following horizontal gene transfer mechanisms involves the uptake of ‘naked’
DNA from the environment?
A. Transformation
B. Transduction
C. Conjugation
D. Transposition
Answer: A
