WGU D311 Microbiology OA Exam Prep (2026) – 226 Practice OA
Questions & Study Guide | Guarantee Pass
Questions 1–226
1. Which structure distinguishes prokaryotic cells from eukaryotic
cells?
A) Nucleus
B) Mitochondria
C) Peptidoglycan cell wall
D) Endoplasmic reticulum
Answer C: Peptidoglycan cell wall
Rationale: Prokaryotic cells have a peptidoglycan cell wall, which is
absent in eukaryotic cells.
,2. Which of the following microorganisms lacks a true nucleus and
membrane-bound organelles?
A) Protozoa
B) Fungi
C) Bacteria
D) Helminths
Answer C: Bacteria
Rationale: Bacteria are prokaryotes, meaning their genetic material is
not enclosed within a nuclear membrane and they lack organelles like
mitochondria.
3. Which microscope uses a beam of electrons to visualize the
surface of a specimen?
A) Phase-contrast microscope
B) Scanning electron microscope (SEM)
C) Transmission electron microscope (TEM)
D) Fluorescence microscope
Answer B: Scanning electron microscope (SEM)
,Rationale: SEM scans the surface with electrons to produce 3D-like
images of surface topography.
4. What is the primary function of the bacterial capsule?
A) Protein synthesis
B) Motility
C) Protection from phagocytosis
D) DNA replication
Answer C: Protection from phagocytosis
Rationale: The capsule is a virulence factor that prevents immune
cells from engulfing the bacterium.
5. Which Gram-positive bacterium produces endospores?
A) Escherichia coli
B) Neisseria gonorrhoeae
C) Bacillus anthracis
D) Treponema pallidum
Answer C: Bacillus anthracis
, Rationale: Bacillus and Clostridium are Gram-positive, endospore-
forming genera.
6. The term "obligate aerobe" refers to an organism that requires:
A) No oxygen
B) Low oxygen levels
C) Oxygen for growth
D) Carbon dioxide only
Answer C: Oxygen for growth
Rationale: Obligate aerobes must have oxygen for cellular respiration
and cannot grow without it.
7. Which of the following is a component of the Gram-negative
outer membrane?
A) Teichoic acid
B) Lipopolysaccharide (LPS)
C) Peptidoglycan only
D) Mycolic acid
Answer B: Lipopolysaccharide (LPS)
Questions & Study Guide | Guarantee Pass
Questions 1–226
1. Which structure distinguishes prokaryotic cells from eukaryotic
cells?
A) Nucleus
B) Mitochondria
C) Peptidoglycan cell wall
D) Endoplasmic reticulum
Answer C: Peptidoglycan cell wall
Rationale: Prokaryotic cells have a peptidoglycan cell wall, which is
absent in eukaryotic cells.
,2. Which of the following microorganisms lacks a true nucleus and
membrane-bound organelles?
A) Protozoa
B) Fungi
C) Bacteria
D) Helminths
Answer C: Bacteria
Rationale: Bacteria are prokaryotes, meaning their genetic material is
not enclosed within a nuclear membrane and they lack organelles like
mitochondria.
3. Which microscope uses a beam of electrons to visualize the
surface of a specimen?
A) Phase-contrast microscope
B) Scanning electron microscope (SEM)
C) Transmission electron microscope (TEM)
D) Fluorescence microscope
Answer B: Scanning electron microscope (SEM)
,Rationale: SEM scans the surface with electrons to produce 3D-like
images of surface topography.
4. What is the primary function of the bacterial capsule?
A) Protein synthesis
B) Motility
C) Protection from phagocytosis
D) DNA replication
Answer C: Protection from phagocytosis
Rationale: The capsule is a virulence factor that prevents immune
cells from engulfing the bacterium.
5. Which Gram-positive bacterium produces endospores?
A) Escherichia coli
B) Neisseria gonorrhoeae
C) Bacillus anthracis
D) Treponema pallidum
Answer C: Bacillus anthracis
, Rationale: Bacillus and Clostridium are Gram-positive, endospore-
forming genera.
6. The term "obligate aerobe" refers to an organism that requires:
A) No oxygen
B) Low oxygen levels
C) Oxygen for growth
D) Carbon dioxide only
Answer C: Oxygen for growth
Rationale: Obligate aerobes must have oxygen for cellular respiration
and cannot grow without it.
7. Which of the following is a component of the Gram-negative
outer membrane?
A) Teichoic acid
B) Lipopolysaccharide (LPS)
C) Peptidoglycan only
D) Mycolic acid
Answer B: Lipopolysaccharide (LPS)
