PORTAGE LEARNING
Bachelor of Science in Nursing (BSN)
BIOL 271 / BIOL 271 Module 5 — Microbiology
Academic Year: 2026/2027 Module 5 Exam · Question Bank NCLEX-style
Q1 Streptococcus is most often streaked onto which type of agar?
A. Blood agar
B. MacConkey agar
C. EMB agar
D. MSA
CORRECT ANSWER: A. Blood agar
— RATIONALE
Blood agar is the preferred medium for Streptococcus because it supports growth of
fastidious species and allows observation of hemolytic patterns (alpha, beta, gamma)
which are critical for identification.
Q2 A facultative anaerobe is capable of growth under:
A. Aerobic conditions only
B. Anaerobic conditions only
C. Both aerobic and anaerobic conditions
D. Neither aerobic nor anaerobic conditions
CORRECT ANSWER: C. Both aerobic and anaerobic conditions
— RATIONALE
Facultative anaerobes can switch between aerobic respiration (when oxygen is available)
and fermentation or anaerobic respiration (when oxygen is absent). This versatility allows
them to colonize various environments.
,Q3 If left untreated, what are the symptoms of syphilis?
A. Infertility and pelvic inflammatory disease
B. Paralysis, blindness, dementia
C. Cardiac and neurological complications
D. Urethritis and discharge
CORRECT ANSWER: B. Paralysis, blindness, dementia
— RATIONALE
Untreated syphilis can progress to the late (tertiary) stage, causing severe complications
such as neurosyphilis (paralysis, dementia, blindness), cardiovascular damage (aortic
aneurysms), and gummas (chronic granulomatous lesions).
Q4 True or False. Although TB must be inhaled and reside in the lung in order
to cause infection, TB can also spread to the brain, spine, and kidneys.
A. True
B. False
CORRECT ANSWER: A. True
— RATIONALE
TB primarily affects the lungs but can disseminate via the bloodstream to extrapulmonary
sites such as the brain (TB meningitis), spine (Pott's disease), and kidneys (renal TB). This
occurs more commonly in immunocompromised individuals.
, Q5 Why does the alpha toxin (perfringolysin) produced during an infection of
gas gangrene cause cell death?
A. It binds to DNA and prevents replication
B. It forms pores in the plasma membrane of host cells, causing ion flux and lysis
C. It inhibits protein synthesis
D. It causes apoptosis
CORRECT ANSWER:
B. It forms pores in the plasma membrane of host cells, causing ion flux and
lysis
— RATIONALE
Perfringolysin (alpha-toxin) is a pore-forming toxin that inserts into the plasma
membrane of host cells, creating channels that disrupt ion homeostasis. This leads to
uncontrolled ion flux, osmotic imbalance, and eventual cell lysis and death.
Q6 What are the symptoms of conjunctivitis?
A. Infection of thin, transparent scleral tissue
B. Infection occurs at time of birth
C. Childhood skin disease near mouth/nose
D. Ruptured pustules treated with penicillin
CORRECT ANSWER: A. Infection of thin, transparent scleral tissue
— RATIONALE
Conjunctivitis (pink eye) is an inflammation of the conjunctiva (the thin, transparent tissue
covering the sclera and inner eyelid). It can be caused by bacteria (S. aureus,
Streptococcus) or viruses.
Bachelor of Science in Nursing (BSN)
BIOL 271 / BIOL 271 Module 5 — Microbiology
Academic Year: 2026/2027 Module 5 Exam · Question Bank NCLEX-style
Q1 Streptococcus is most often streaked onto which type of agar?
A. Blood agar
B. MacConkey agar
C. EMB agar
D. MSA
CORRECT ANSWER: A. Blood agar
— RATIONALE
Blood agar is the preferred medium for Streptococcus because it supports growth of
fastidious species and allows observation of hemolytic patterns (alpha, beta, gamma)
which are critical for identification.
Q2 A facultative anaerobe is capable of growth under:
A. Aerobic conditions only
B. Anaerobic conditions only
C. Both aerobic and anaerobic conditions
D. Neither aerobic nor anaerobic conditions
CORRECT ANSWER: C. Both aerobic and anaerobic conditions
— RATIONALE
Facultative anaerobes can switch between aerobic respiration (when oxygen is available)
and fermentation or anaerobic respiration (when oxygen is absent). This versatility allows
them to colonize various environments.
,Q3 If left untreated, what are the symptoms of syphilis?
A. Infertility and pelvic inflammatory disease
B. Paralysis, blindness, dementia
C. Cardiac and neurological complications
D. Urethritis and discharge
CORRECT ANSWER: B. Paralysis, blindness, dementia
— RATIONALE
Untreated syphilis can progress to the late (tertiary) stage, causing severe complications
such as neurosyphilis (paralysis, dementia, blindness), cardiovascular damage (aortic
aneurysms), and gummas (chronic granulomatous lesions).
Q4 True or False. Although TB must be inhaled and reside in the lung in order
to cause infection, TB can also spread to the brain, spine, and kidneys.
A. True
B. False
CORRECT ANSWER: A. True
— RATIONALE
TB primarily affects the lungs but can disseminate via the bloodstream to extrapulmonary
sites such as the brain (TB meningitis), spine (Pott's disease), and kidneys (renal TB). This
occurs more commonly in immunocompromised individuals.
, Q5 Why does the alpha toxin (perfringolysin) produced during an infection of
gas gangrene cause cell death?
A. It binds to DNA and prevents replication
B. It forms pores in the plasma membrane of host cells, causing ion flux and lysis
C. It inhibits protein synthesis
D. It causes apoptosis
CORRECT ANSWER:
B. It forms pores in the plasma membrane of host cells, causing ion flux and
lysis
— RATIONALE
Perfringolysin (alpha-toxin) is a pore-forming toxin that inserts into the plasma
membrane of host cells, creating channels that disrupt ion homeostasis. This leads to
uncontrolled ion flux, osmotic imbalance, and eventual cell lysis and death.
Q6 What are the symptoms of conjunctivitis?
A. Infection of thin, transparent scleral tissue
B. Infection occurs at time of birth
C. Childhood skin disease near mouth/nose
D. Ruptured pustules treated with penicillin
CORRECT ANSWER: A. Infection of thin, transparent scleral tissue
— RATIONALE
Conjunctivitis (pink eye) is an inflammation of the conjunctiva (the thin, transparent tissue
covering the sclera and inner eyelid). It can be caused by bacteria (S. aureus,
Streptococcus) or viruses.
