BIOD 171 Module 5: Exam Portage Learning Questions and
Answers 2026 Practice Set
1. Which of the following bacteria is the most common cause of "Strep Throat"
and can lead to Rheumatic Fever if left untreated?
A) Staphylococcus aureus
B) Streptococcus pyogenes
C) Streptococcus pneumoniae
D) Klebsiella pneumoniae
Rationale: S. pyogenes (Group A Strep) is the causative agent of pharyngitis. It is
known for its ability to cause secondary autoimmune complications like Rheumatic
Fever due to molecular mimicry.
2. Which pathogen is a Gram-positive, anaerobic, spore-forming rod known for
causing severe diarrhea, often following a course of broad-spectrum antibiotics?
A) Escherichia coli
B) Salmonella enterica
C) Clostridioides difficile (C. diff)
D) Listeria monocytogenes
Rationale: C. diff thrives in the gut when the normal flora is depleted by antibiotics,
producing toxins that cause pseudomembranous colitis.
3. "Bull's-eye" rash (Erythema migrans) is a signature clinical sign of which
disease?
A) Syphilis
B) Lyme Disease
C) Rocky Mountain Spotted Fever
D) Measles
Rationale: Lyme Disease, caused by the spirochete Borrelia burgdorferi, often begins
with this distinct expanding red rash at the site of a tick bite.
4. Which of the following is the causative agent of the Bubonic Plague?
A) Bacillus anthracis
B) Yersinia pestis
C) Francisella tularensis
D) Bordetella pertussis
,Rationale: Y. pestis is a Gram-negative rod transmitted by fleas; it infects the lymph
nodes, causing "buboes."
5. Mycobacterium tuberculosis is highly resistant to many disinfectants and the
immune system primarily because of:
A) Its ability to form endospores
B) The waxy mycolic acid in its cell wall
C) Its rapid rate of division
D) Its production of potent exotoxins
Rationale: The waxy lipid (mycolic acid) prevents many chemicals from entering the
cell and allows the bacteria to survive inside host macrophages.
6. Which virus is responsible for causing "Chickenpox" and can later reactivate
as "Shingles"?
A) Human Papillomavirus (HPV)
B) Epstein-Barr Virus (EBV)
C) Varicella-Zoster Virus (VZV)
D) Herpes Simplex Virus 1 (HSV-1)
Rationale: VZV stays dormant in the nerve ganglia after the initial chickenpox infection
and can re-emerge later in life as painful shingles.
7. Which Gram-negative, "comma-shaped" bacterium causes profuse, watery
"rice-water stools"?
A) Vibrio cholerae
B) Shigella dysenteriae
C) Campylobacter jejuni
D) Helicobacter pylori
Rationale: V. cholerae produces a toxin that causes the intestines to shed massive
amounts of water and electrolytes.
8. The "DTaP" vaccine protects against Diphtheria, Tetanus, and which other
respiratory disease?
A) Tuberculosis
B) Influenza
C) Pertussis (Whooping Cough)
D) Pneumonia
Rationale: Pertussis is caused by Bordetella pertussis, which attaches to the cilia of the
respiratory tract.
9. Which of the following is a key characteristic of Staphylococcus aureus?
A) It is Coagulase-positive
, B) It is Gram-negative
C) It is a strict anaerobe
D) It cannot grow on salt
Rationale: S. aureus is distinguished from other staphylococci by its ability to produce
the enzyme coagulase, which clots blood plasma.
10. "Lockjaw" is a common symptom of which disease caused by a potent
neurotoxin?
A) Botulism
B) Tetanus
C) Anthrax
D) Gas Gangrene
Rationale: Clostridium tetani produces tetanospasmin, which blocks inhibitory
neurotransmitters, leading to continuous muscle contraction (spastic paralysis).
Would you like to continue with questions 11–50 for Module 5, or move to Module 6
(Immunology)?
1 site
• eBook Reader
Cholera toxin from bacterium Vibrio cholerae, and enterotoxins of certain strains of
Escherichia coli act in this way on intestina...
JaypeeDigital
1-50
Continuing with
Module 5: Microbial Diseases. These questions focus on specific bacterial, viral, and
fungal pathogens, their transmission, and clinical presentations.
11. Which pathogen causes "Rice-water stools" and is often spread through
contaminated water?
Answers 2026 Practice Set
1. Which of the following bacteria is the most common cause of "Strep Throat"
and can lead to Rheumatic Fever if left untreated?
A) Staphylococcus aureus
B) Streptococcus pyogenes
C) Streptococcus pneumoniae
D) Klebsiella pneumoniae
Rationale: S. pyogenes (Group A Strep) is the causative agent of pharyngitis. It is
known for its ability to cause secondary autoimmune complications like Rheumatic
Fever due to molecular mimicry.
2. Which pathogen is a Gram-positive, anaerobic, spore-forming rod known for
causing severe diarrhea, often following a course of broad-spectrum antibiotics?
A) Escherichia coli
B) Salmonella enterica
C) Clostridioides difficile (C. diff)
D) Listeria monocytogenes
Rationale: C. diff thrives in the gut when the normal flora is depleted by antibiotics,
producing toxins that cause pseudomembranous colitis.
3. "Bull's-eye" rash (Erythema migrans) is a signature clinical sign of which
disease?
A) Syphilis
B) Lyme Disease
C) Rocky Mountain Spotted Fever
D) Measles
Rationale: Lyme Disease, caused by the spirochete Borrelia burgdorferi, often begins
with this distinct expanding red rash at the site of a tick bite.
4. Which of the following is the causative agent of the Bubonic Plague?
A) Bacillus anthracis
B) Yersinia pestis
C) Francisella tularensis
D) Bordetella pertussis
,Rationale: Y. pestis is a Gram-negative rod transmitted by fleas; it infects the lymph
nodes, causing "buboes."
5. Mycobacterium tuberculosis is highly resistant to many disinfectants and the
immune system primarily because of:
A) Its ability to form endospores
B) The waxy mycolic acid in its cell wall
C) Its rapid rate of division
D) Its production of potent exotoxins
Rationale: The waxy lipid (mycolic acid) prevents many chemicals from entering the
cell and allows the bacteria to survive inside host macrophages.
6. Which virus is responsible for causing "Chickenpox" and can later reactivate
as "Shingles"?
A) Human Papillomavirus (HPV)
B) Epstein-Barr Virus (EBV)
C) Varicella-Zoster Virus (VZV)
D) Herpes Simplex Virus 1 (HSV-1)
Rationale: VZV stays dormant in the nerve ganglia after the initial chickenpox infection
and can re-emerge later in life as painful shingles.
7. Which Gram-negative, "comma-shaped" bacterium causes profuse, watery
"rice-water stools"?
A) Vibrio cholerae
B) Shigella dysenteriae
C) Campylobacter jejuni
D) Helicobacter pylori
Rationale: V. cholerae produces a toxin that causes the intestines to shed massive
amounts of water and electrolytes.
8. The "DTaP" vaccine protects against Diphtheria, Tetanus, and which other
respiratory disease?
A) Tuberculosis
B) Influenza
C) Pertussis (Whooping Cough)
D) Pneumonia
Rationale: Pertussis is caused by Bordetella pertussis, which attaches to the cilia of the
respiratory tract.
9. Which of the following is a key characteristic of Staphylococcus aureus?
A) It is Coagulase-positive
, B) It is Gram-negative
C) It is a strict anaerobe
D) It cannot grow on salt
Rationale: S. aureus is distinguished from other staphylococci by its ability to produce
the enzyme coagulase, which clots blood plasma.
10. "Lockjaw" is a common symptom of which disease caused by a potent
neurotoxin?
A) Botulism
B) Tetanus
C) Anthrax
D) Gas Gangrene
Rationale: Clostridium tetani produces tetanospasmin, which blocks inhibitory
neurotransmitters, leading to continuous muscle contraction (spastic paralysis).
Would you like to continue with questions 11–50 for Module 5, or move to Module 6
(Immunology)?
1 site
• eBook Reader
Cholera toxin from bacterium Vibrio cholerae, and enterotoxins of certain strains of
Escherichia coli act in this way on intestina...
JaypeeDigital
1-50
Continuing with
Module 5: Microbial Diseases. These questions focus on specific bacterial, viral, and
fungal pathogens, their transmission, and clinical presentations.
11. Which pathogen causes "Rice-water stools" and is often spread through
contaminated water?
