2026 Nursing Bacteriology Study Guide Practice
Questions • Answer Explanations • Bacterial
Pathogens • Infections • Transmission • Antibiotic
Therapy • Specimen Collection
SECTION I: BACTERIAL STRUCTURE, CLASSIFICATION & GROWTH
(Questions 1–25)
1. A nurse is reviewing the structure of bacteria. Which structure is
responsible for bacterial motility?
A. Pili
B. Capsule
C. Flagella
D. Cell wall
Rationale: Flagella are long, whip-like appendages that provide motility for
bacteria. Pili are involved in attachment and conjugation, the capsule provides
protection, and the cell wall provides structural support.
2. A nurse is reviewing the structure of bacteria. Which structure helps
bacteria adhere to surfaces and resist phagocytosis?
A. Flagella
B. Capsule
C. Ribosomes
D. Nucleoid
Rationale: The capsule is a polysaccharide layer outside the cell wall that helps
bacteria adhere to surfaces and resist phagocytosis by host immune cells.
,3. A nurse is reviewing the structure of bacteria. Which structure is involved
in horizontal gene transfer between bacteria?
A. Flagella
B. Capsule
C. Pili
D. Cell membrane
Rationale: Pili (sex pili) are involved in conjugation, a form of horizontal gene
transfer where genetic material is transferred between bacteria.
4. A nurse is reviewing the classification of bacteria by shape. Which term
describes spherical bacteria?
A. Bacilli
B. Cocci
C. Spirilla
D. Vibrios
Rationale: Cocci are spherical bacteria. Bacilli are rod-shaped, spirilla are spiral-
shaped, and vibrios are comma-shaped.
5. A nurse is reviewing the classification of bacteria by shape. Which term
describes rod-shaped bacteria?
A. Cocci
B. Bacilli
C. Spirilla
D. Spirochetes
Rationale: Bacilli are rod-shaped bacteria. Cocci are spherical, spirilla are spiral-
shaped, and spirochetes are flexible spiral-shaped bacteria.
,6. A nurse is reviewing the classification of bacteria by shape. Which term
describes spiral-shaped bacteria?
A. Cocci
B. Bacilli
C. Spirilla
D. Vibrios
Rationale: Spirilla are spiral-shaped bacteria. Cocci are spherical, bacilli are rod-
shaped, and vibrios are comma-shaped.
7. A nurse is reviewing the classification of bacteria by Gram stain. Which
color indicates Gram-positive bacteria?
A. Red/pink
B. Purple/blue
C. Green
D. Yellow
Rationale: Gram-positive bacteria retain the crystal violet stain and appear
purple/blue under the microscope. Gram-negative bacteria appear red/pink because
they do not retain the crystal violet stain.
8. A nurse is reviewing the classification of bacteria by Gram stain. Which
color indicates Gram-negative bacteria?
A. Red/pink
B. Purple/blue
C. Green
D. Yellow
Rationale: Gram-negative bacteria do not retain the crystal violet stain and appear
red/pink after counterstaining with safranin.
, 9. A nurse is reviewing the structure of Gram-positive bacteria. Which
component is thick and retains the crystal violet stain?
A. Outer membrane
B. Peptidoglycan layer
C. Lipopolysaccharide layer
D. Capsule
Rationale: Gram-positive bacteria have a thick peptidoglycan layer that retains the
crystal violet stain. Gram-negative bacteria have a thin peptidoglycan layer and an
outer membrane containing lipopolysaccharide.
10. A nurse is reviewing the structure of Gram-negative bacteria. Which
component is responsible for endotoxic shock?
A. Peptidoglycan
B. Lipopolysaccharide (LPS)
C. Capsule
D. Flagella
Rationale: Lipopolysaccharide (LPS) in the outer membrane of Gram-negative
bacteria is an endotoxin that can cause endotoxic shock (septic shock) when
released into the bloodstream.
11. A nurse is reviewing the classification of bacteria by oxygen requirements.
Which term describes bacteria that require oxygen to survive?
A. Anaerobes
B. Obligate aerobes
C. Facultative anaerobes
D. Microaerophiles
Rationale: Obligate aerobes require oxygen to survive. Anaerobes die in the
presence of oxygen, facultative anaerobes can survive with or without oxygen, and
microaerophiles require low levels of oxygen.
Questions • Answer Explanations • Bacterial
Pathogens • Infections • Transmission • Antibiotic
Therapy • Specimen Collection
SECTION I: BACTERIAL STRUCTURE, CLASSIFICATION & GROWTH
(Questions 1–25)
1. A nurse is reviewing the structure of bacteria. Which structure is
responsible for bacterial motility?
A. Pili
B. Capsule
C. Flagella
D. Cell wall
Rationale: Flagella are long, whip-like appendages that provide motility for
bacteria. Pili are involved in attachment and conjugation, the capsule provides
protection, and the cell wall provides structural support.
2. A nurse is reviewing the structure of bacteria. Which structure helps
bacteria adhere to surfaces and resist phagocytosis?
A. Flagella
B. Capsule
C. Ribosomes
D. Nucleoid
Rationale: The capsule is a polysaccharide layer outside the cell wall that helps
bacteria adhere to surfaces and resist phagocytosis by host immune cells.
,3. A nurse is reviewing the structure of bacteria. Which structure is involved
in horizontal gene transfer between bacteria?
A. Flagella
B. Capsule
C. Pili
D. Cell membrane
Rationale: Pili (sex pili) are involved in conjugation, a form of horizontal gene
transfer where genetic material is transferred between bacteria.
4. A nurse is reviewing the classification of bacteria by shape. Which term
describes spherical bacteria?
A. Bacilli
B. Cocci
C. Spirilla
D. Vibrios
Rationale: Cocci are spherical bacteria. Bacilli are rod-shaped, spirilla are spiral-
shaped, and vibrios are comma-shaped.
5. A nurse is reviewing the classification of bacteria by shape. Which term
describes rod-shaped bacteria?
A. Cocci
B. Bacilli
C. Spirilla
D. Spirochetes
Rationale: Bacilli are rod-shaped bacteria. Cocci are spherical, spirilla are spiral-
shaped, and spirochetes are flexible spiral-shaped bacteria.
,6. A nurse is reviewing the classification of bacteria by shape. Which term
describes spiral-shaped bacteria?
A. Cocci
B. Bacilli
C. Spirilla
D. Vibrios
Rationale: Spirilla are spiral-shaped bacteria. Cocci are spherical, bacilli are rod-
shaped, and vibrios are comma-shaped.
7. A nurse is reviewing the classification of bacteria by Gram stain. Which
color indicates Gram-positive bacteria?
A. Red/pink
B. Purple/blue
C. Green
D. Yellow
Rationale: Gram-positive bacteria retain the crystal violet stain and appear
purple/blue under the microscope. Gram-negative bacteria appear red/pink because
they do not retain the crystal violet stain.
8. A nurse is reviewing the classification of bacteria by Gram stain. Which
color indicates Gram-negative bacteria?
A. Red/pink
B. Purple/blue
C. Green
D. Yellow
Rationale: Gram-negative bacteria do not retain the crystal violet stain and appear
red/pink after counterstaining with safranin.
, 9. A nurse is reviewing the structure of Gram-positive bacteria. Which
component is thick and retains the crystal violet stain?
A. Outer membrane
B. Peptidoglycan layer
C. Lipopolysaccharide layer
D. Capsule
Rationale: Gram-positive bacteria have a thick peptidoglycan layer that retains the
crystal violet stain. Gram-negative bacteria have a thin peptidoglycan layer and an
outer membrane containing lipopolysaccharide.
10. A nurse is reviewing the structure of Gram-negative bacteria. Which
component is responsible for endotoxic shock?
A. Peptidoglycan
B. Lipopolysaccharide (LPS)
C. Capsule
D. Flagella
Rationale: Lipopolysaccharide (LPS) in the outer membrane of Gram-negative
bacteria is an endotoxin that can cause endotoxic shock (septic shock) when
released into the bloodstream.
11. A nurse is reviewing the classification of bacteria by oxygen requirements.
Which term describes bacteria that require oxygen to survive?
A. Anaerobes
B. Obligate aerobes
C. Facultative anaerobes
D. Microaerophiles
Rationale: Obligate aerobes require oxygen to survive. Anaerobes die in the
presence of oxygen, facultative anaerobes can survive with or without oxygen, and
microaerophiles require low levels of oxygen.
