PORTAGE LEARNING
Bachelor of Science in Biology (BS)
BIOL 271 — Microbiology
Academic Year: 2026/2027
Module 3 Exam Practice — Complete Pathogen Bank
Portage Learning — Rigorous & Competency-Based
Question 1
Which Gram-positive rod is acid-fast positive and forms protective tubercles in the
lungs?
A. Listeria monocytogenes
B. Mycobacterium tuberculosis
C. Corynebacterium diphtheriae
D. Bacillus anthracis
CORRECT ANSWER B. Mycobacterium tuberculosis
Rationale
Mycobacterium tuberculosis is an acid-fast positive rod that forms protective tubercles in
the lungs, causing tuberculosis. Its waxy mycolic acid coat makes it acid-fast and resistant
to standard Gram staining.
, Question 2
Which protozoan is waterborne and causes smelly, greasy diarrhea that floats?
A. Trichomonas sp.
B. Giardia sp.
C. Trypanosoma sp.
D. Leishmania sp.
CORRECT ANSWER B. Giardia sp.
Rationale
Giardia sp. is a waterborne protozoan that causes giardiasis, characterized by smelly, greasy
diarrhea that floats due to fat malabsorption. It is one of the most common causes of
waterborne diarrhea.
Question 3
Which Gram-negative diplococcus causes a sexually transmitted disease?
A. Neisseria gonorrhoeae
B. Bordetella pertussis
C. Legionella pneumophila
D. Pseudomonas aeruginosa
CORRECT ANSWER A. Neisseria gonorrhoeae
Rationale
Neisseria gonorrhoeae is a Gram-negative diplococcus that causes the sexually transmitted
infection gonorrhea. It primarily infects the mucous membranes of the reproductive tract.
, Question 4
Which Gram-negative rod is known for causing Hemolytic Uremic Syndrome
(kidney failure)?
A. Salmonella typhi
B. Yersinia pestis
C. Escherichia coli O157:H7
D. Vibrio cholerae
CORRECT ANSWER C. Escherichia coli O157:H7
Rationale
Escherichia coli O157:H7 is a Gram-negative rod that produces Shiga toxin, causing
Hemolytic Uremic Syndrome (HUS), which leads to kidney failure. It is often contracted
through contaminated food.
Question 5
Which virus is the leading cause of cruise ship gastroenteritis and is resistant to
alcohol sanitizers?
A. Polio
B. Norovirus
C. Rubella
D. HIV
CORRECT ANSWER B. Norovirus
Rationale
Norovirus is the leading cause of cruise ship gastroenteritis. It is highly contagious and
resistant to alcohol-based sanitizers, requiring thorough handwashing with soap and water.
, Question 6
Which Gram-positive rod causes lockjaw, muscle spasms, and opisthotonus?
A. Clostridium tetani
B. Clostridium botulinum
C. Clostridium difficile
D. Clostridium perfringens
CORRECT ANSWER A. Clostridium tetani
Rationale
Clostridium tetani is a Gram-positive, endospore-forming rod that produces tetanospasmin
toxin. It causes lockjaw (trismus), muscle spasms, and opisthotonus (severe back arching).
Question 7
Which protozoan is transmitted by sand flies and causes cutaneous or visceral
sores?
A. Trypanosoma sp.
B. Leishmania sp.
C. Plasmodium sp.
D. Toxoplasma sp.
CORRECT ANSWER B. Leishmania sp.
Rationale
Leishmania sp. is a protozoan transmitted by sand flies. It causes cutaneous leishmaniasis
(skin sores) or visceral leishmaniasis (organ damage), depending on the species.
Bachelor of Science in Biology (BS)
BIOL 271 — Microbiology
Academic Year: 2026/2027
Module 3 Exam Practice — Complete Pathogen Bank
Portage Learning — Rigorous & Competency-Based
Question 1
Which Gram-positive rod is acid-fast positive and forms protective tubercles in the
lungs?
A. Listeria monocytogenes
B. Mycobacterium tuberculosis
C. Corynebacterium diphtheriae
D. Bacillus anthracis
CORRECT ANSWER B. Mycobacterium tuberculosis
Rationale
Mycobacterium tuberculosis is an acid-fast positive rod that forms protective tubercles in
the lungs, causing tuberculosis. Its waxy mycolic acid coat makes it acid-fast and resistant
to standard Gram staining.
, Question 2
Which protozoan is waterborne and causes smelly, greasy diarrhea that floats?
A. Trichomonas sp.
B. Giardia sp.
C. Trypanosoma sp.
D. Leishmania sp.
CORRECT ANSWER B. Giardia sp.
Rationale
Giardia sp. is a waterborne protozoan that causes giardiasis, characterized by smelly, greasy
diarrhea that floats due to fat malabsorption. It is one of the most common causes of
waterborne diarrhea.
Question 3
Which Gram-negative diplococcus causes a sexually transmitted disease?
A. Neisseria gonorrhoeae
B. Bordetella pertussis
C. Legionella pneumophila
D. Pseudomonas aeruginosa
CORRECT ANSWER A. Neisseria gonorrhoeae
Rationale
Neisseria gonorrhoeae is a Gram-negative diplococcus that causes the sexually transmitted
infection gonorrhea. It primarily infects the mucous membranes of the reproductive tract.
, Question 4
Which Gram-negative rod is known for causing Hemolytic Uremic Syndrome
(kidney failure)?
A. Salmonella typhi
B. Yersinia pestis
C. Escherichia coli O157:H7
D. Vibrio cholerae
CORRECT ANSWER C. Escherichia coli O157:H7
Rationale
Escherichia coli O157:H7 is a Gram-negative rod that produces Shiga toxin, causing
Hemolytic Uremic Syndrome (HUS), which leads to kidney failure. It is often contracted
through contaminated food.
Question 5
Which virus is the leading cause of cruise ship gastroenteritis and is resistant to
alcohol sanitizers?
A. Polio
B. Norovirus
C. Rubella
D. HIV
CORRECT ANSWER B. Norovirus
Rationale
Norovirus is the leading cause of cruise ship gastroenteritis. It is highly contagious and
resistant to alcohol-based sanitizers, requiring thorough handwashing with soap and water.
, Question 6
Which Gram-positive rod causes lockjaw, muscle spasms, and opisthotonus?
A. Clostridium tetani
B. Clostridium botulinum
C. Clostridium difficile
D. Clostridium perfringens
CORRECT ANSWER A. Clostridium tetani
Rationale
Clostridium tetani is a Gram-positive, endospore-forming rod that produces tetanospasmin
toxin. It causes lockjaw (trismus), muscle spasms, and opisthotonus (severe back arching).
Question 7
Which protozoan is transmitted by sand flies and causes cutaneous or visceral
sores?
A. Trypanosoma sp.
B. Leishmania sp.
C. Plasmodium sp.
D. Toxoplasma sp.
CORRECT ANSWER B. Leishmania sp.
Rationale
Leishmania sp. is a protozoan transmitted by sand flies. It causes cutaneous leishmaniasis
(skin sores) or visceral leishmaniasis (organ damage), depending on the species.
