BIO205 Microbiology
Midterm Exam Review (Qns & Ans)
2025
1. What is the primary role of the Gram staining technique in
microbiology?
A. To measure microbial motility
B. To identify and differentiate bacterial species
C. To quantify the bacterial population
D. To test for bacterial spore production
ANS: B. To identify and differentiate bacterial species
Rationale: Gram staining distinguishes bacteria based on the
composition of their cell walls (Gram-positive or Gram-negative).
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,2. Which microorganism is primarily responsible for causing
tuberculosis?
A. Streptococcus pneumoniae
B. Mycobacterium tuberculosis
C. Escherichia coli
D. Staphylococcus aureus
ANS: B. Mycobacterium tuberculosis
Rationale: Mycobacterium tuberculosis is the causative agent
of tuberculosis, transmitted via respiratory droplets.
3. What does a zone of inhibition indicate in an antimicrobial
susceptibility test?
A. Bacterial motility
B. Microbial resistance
C. Effectiveness of the tested antibiotic
D. Bacterial spore formation
ANS: C. Effectiveness of the tested antibiotic
Rationale: A zone of inhibition shows how well an antibiotic
inhibits bacterial growth.
4. Which of the following is an example of an obligate
anaerobe?
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, A. Staphylococcus aureus
B. Clostridium perfringens
C. Vibrio cholerae
D. Bacillus anthracis
ANS: B. Clostridium perfringens
Rationale: Clostridium species grow in oxygen-free
environments and are obligate anaerobes.
5. What is the role of pili in bacterial cells?
A. Nutrient transport
B. Adherence to host tissues and DNA transfer
C. Cell wall synthesis
D. Energy production
ANS: B. Adherence to host tissues and DNA transfer
Rationale: Pili aid in bacterial adhesion and the transfer of
genetic material via conjugation.
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Fill-in-the-Blank Questions
©2025
Midterm Exam Review (Qns & Ans)
2025
1. What is the primary role of the Gram staining technique in
microbiology?
A. To measure microbial motility
B. To identify and differentiate bacterial species
C. To quantify the bacterial population
D. To test for bacterial spore production
ANS: B. To identify and differentiate bacterial species
Rationale: Gram staining distinguishes bacteria based on the
composition of their cell walls (Gram-positive or Gram-negative).
©2025
,2. Which microorganism is primarily responsible for causing
tuberculosis?
A. Streptococcus pneumoniae
B. Mycobacterium tuberculosis
C. Escherichia coli
D. Staphylococcus aureus
ANS: B. Mycobacterium tuberculosis
Rationale: Mycobacterium tuberculosis is the causative agent
of tuberculosis, transmitted via respiratory droplets.
3. What does a zone of inhibition indicate in an antimicrobial
susceptibility test?
A. Bacterial motility
B. Microbial resistance
C. Effectiveness of the tested antibiotic
D. Bacterial spore formation
ANS: C. Effectiveness of the tested antibiotic
Rationale: A zone of inhibition shows how well an antibiotic
inhibits bacterial growth.
4. Which of the following is an example of an obligate
anaerobe?
©2025
, A. Staphylococcus aureus
B. Clostridium perfringens
C. Vibrio cholerae
D. Bacillus anthracis
ANS: B. Clostridium perfringens
Rationale: Clostridium species grow in oxygen-free
environments and are obligate anaerobes.
5. What is the role of pili in bacterial cells?
A. Nutrient transport
B. Adherence to host tissues and DNA transfer
C. Cell wall synthesis
D. Energy production
ANS: B. Adherence to host tissues and DNA transfer
Rationale: Pili aid in bacterial adhesion and the transfer of
genetic material via conjugation.
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Fill-in-the-Blank Questions
©2025
