WGU D311 OA PRE-ASSESSMENT:
MICROBIOLOGY Complete Pass Mega Bundle |
Updated OA (2025/2026) Verified Questions
with Correct Answers & Detailed Explanations
ABOUT THIS GUIDE
This comprehensive study bundle contains verified exam questions and correct
answers for the WGU D311: Microbiology Objective Assessment (OA) and Pre-
Assessment (PA). The material is curated from the 2025/2026 academic year and
is designed for students enrolled in nursing, healthcare, biology, or pre-med
programs at Western Governors University .
Source References:
• GMO1 / PGMO Pre-Assessment
• WGU D311 Microbiology OA Final Exam
• Verified Multiple Choice Questions with Rationales
SECTION 1: MICROBIAL WORLD & CELL STRUCTURE (Questions 1-30)
1.1 Prokaryotic vs. Eukaryotic Cells
Question 1
Which of the following structures is used by bacteria for motility?
A) Pili
B) Capsule
C) Fimbriae
D) Flagella
Answer: D) Flagella
,Flagella are whip-like appendages that rotate to propel bacterial cells. They are
the primary structures for bacterial motility and taxis (movement in response to
stimuli). Pili and fimbriae are used for attachment, while the capsule is for
protection and immune evasion .
Question 2
A Gram-negative cell wall contains which of the following?
A) Thick peptidoglycan
B) Teichoic acid
C) No outer membrane
D) Lipopolysaccharide (LPS)
Answer: D) Lipopolysaccharide (LPS)
Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane
containing lipopolysaccharide (LPS). LPS is an endotoxin that triggers fever and
inflammation when released. Gram-positive bacteria have thick peptidoglycan
with teichoic acids but no outer membrane .
Question 3
What is the defining characteristic of eukaryotes?
A) They are always multicellular
B) They have a nucleus
C) They lack membrane-bound organelles
D) They reproduce only asexually
Answer: B) They have a nucleus
Eukaryotic cells are defined by the presence of a true nucleus enclosed by a
nuclear membrane and membrane-bound organelles (mitochondria, endoplasmic
reticulum, Golgi apparatus). Prokaryotes (bacteria and archaea) lack these
structures .
,Question 4
What are characteristics of Prokaryotic Cells (Bacteria)?
A) Have a nucleus and membrane-bound organelles
B) Single-celled, no nucleus, multiple shapes, cell walls with peptidoglycan
C) Always multicellular with chitin cell walls
D) Contain linear histone-wrapped chromosomes
Answer: B) Single-celled, no nucleus, multiple shapes, cell walls with
peptidoglycan
Prokaryotic cells are unicellular, lack a nucleus and membrane-bound organelles,
and have cell walls made of peptidoglycan. They come in various shapes: cocci
(spherical), bacilli (rod-shaped), spirilla (spiral), and vibrio (curved rod). Eukaryotes
have a nucleus and membrane-bound organelles .
Question 5
What is the significance of microorganisms containing a thick coat of
peptidoglycan within the cell wall?
A) They are classified as Gram-negative
B) They are typically classified as Gram-positive bacteria
C) They are resistant to all antibiotics
D) They cannot form endospores
Answer: B) They are typically classified as Gram-positive bacteria
Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal
violet stain during Gram staining, appearing purple. The thick peptidoglycan
provides structural integrity and protection against osmotic pressure but does not
confer antibiotic resistance .
Question 6
Why are viruses considered acellular?
A) They lack a cell wall
B) They cannot reproduce without a host
, C) They are too small to see
D) They contain DNA but not RNA
Answer: B) They cannot reproduce without a host
Viruses are acellular because they lack cellular structure and cannot reproduce
independently. They are obligate intracellular parasites that rely on host cell
machinery for replication. They contain either DNA or RNA, never both .
Question 7
A key structural difference between Gram-positive and Gram-negative bacteria is:
A) Gram-positive bacteria have an outer membrane
B) Gram-negative bacteria have a thick peptidoglycan layer
C) Gram-positive bacteria have teichoic acids in their cell wall
D) Gram-negative bacteria lack lipopolysaccharide
Answer: C) Gram-positive bacteria have teichoic acids in their cell wall
Teichoic acids are unique to Gram-positive cell walls and are not found in Gram-
negative bacteria. Gram-positive bacteria have a thick peptidoglycan layer, while
Gram-negative bacteria have a thin peptidoglycan layer surrounded by an outer
membrane containing lipopolysaccharide (LPS) .
Question 8
Which of the following describes the cell wall structure of Gram-positive bacteria?
A) Thin layer of peptidoglycan with an outer membrane containing LPS
B) Thick layer of peptidoglycan with teichoic acids
C) No peptidoglycan, composed of pseudopeptidoglycan
D) Outer membrane of lipoteichoic acid
Answer: B) Thick layer of peptidoglycan with teichoic acids
*Gram-positive bacteria have a thick (20-80 nm) peptidoglycan layer that retains
the crystal violet stain. Teichoic acids (including lipoteichoic acid) are embedded
in the peptidoglycan and contribute to cell wall structure and adhesion .*
MICROBIOLOGY Complete Pass Mega Bundle |
Updated OA (2025/2026) Verified Questions
with Correct Answers & Detailed Explanations
ABOUT THIS GUIDE
This comprehensive study bundle contains verified exam questions and correct
answers for the WGU D311: Microbiology Objective Assessment (OA) and Pre-
Assessment (PA). The material is curated from the 2025/2026 academic year and
is designed for students enrolled in nursing, healthcare, biology, or pre-med
programs at Western Governors University .
Source References:
• GMO1 / PGMO Pre-Assessment
• WGU D311 Microbiology OA Final Exam
• Verified Multiple Choice Questions with Rationales
SECTION 1: MICROBIAL WORLD & CELL STRUCTURE (Questions 1-30)
1.1 Prokaryotic vs. Eukaryotic Cells
Question 1
Which of the following structures is used by bacteria for motility?
A) Pili
B) Capsule
C) Fimbriae
D) Flagella
Answer: D) Flagella
,Flagella are whip-like appendages that rotate to propel bacterial cells. They are
the primary structures for bacterial motility and taxis (movement in response to
stimuli). Pili and fimbriae are used for attachment, while the capsule is for
protection and immune evasion .
Question 2
A Gram-negative cell wall contains which of the following?
A) Thick peptidoglycan
B) Teichoic acid
C) No outer membrane
D) Lipopolysaccharide (LPS)
Answer: D) Lipopolysaccharide (LPS)
Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane
containing lipopolysaccharide (LPS). LPS is an endotoxin that triggers fever and
inflammation when released. Gram-positive bacteria have thick peptidoglycan
with teichoic acids but no outer membrane .
Question 3
What is the defining characteristic of eukaryotes?
A) They are always multicellular
B) They have a nucleus
C) They lack membrane-bound organelles
D) They reproduce only asexually
Answer: B) They have a nucleus
Eukaryotic cells are defined by the presence of a true nucleus enclosed by a
nuclear membrane and membrane-bound organelles (mitochondria, endoplasmic
reticulum, Golgi apparatus). Prokaryotes (bacteria and archaea) lack these
structures .
,Question 4
What are characteristics of Prokaryotic Cells (Bacteria)?
A) Have a nucleus and membrane-bound organelles
B) Single-celled, no nucleus, multiple shapes, cell walls with peptidoglycan
C) Always multicellular with chitin cell walls
D) Contain linear histone-wrapped chromosomes
Answer: B) Single-celled, no nucleus, multiple shapes, cell walls with
peptidoglycan
Prokaryotic cells are unicellular, lack a nucleus and membrane-bound organelles,
and have cell walls made of peptidoglycan. They come in various shapes: cocci
(spherical), bacilli (rod-shaped), spirilla (spiral), and vibrio (curved rod). Eukaryotes
have a nucleus and membrane-bound organelles .
Question 5
What is the significance of microorganisms containing a thick coat of
peptidoglycan within the cell wall?
A) They are classified as Gram-negative
B) They are typically classified as Gram-positive bacteria
C) They are resistant to all antibiotics
D) They cannot form endospores
Answer: B) They are typically classified as Gram-positive bacteria
Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal
violet stain during Gram staining, appearing purple. The thick peptidoglycan
provides structural integrity and protection against osmotic pressure but does not
confer antibiotic resistance .
Question 6
Why are viruses considered acellular?
A) They lack a cell wall
B) They cannot reproduce without a host
, C) They are too small to see
D) They contain DNA but not RNA
Answer: B) They cannot reproduce without a host
Viruses are acellular because they lack cellular structure and cannot reproduce
independently. They are obligate intracellular parasites that rely on host cell
machinery for replication. They contain either DNA or RNA, never both .
Question 7
A key structural difference between Gram-positive and Gram-negative bacteria is:
A) Gram-positive bacteria have an outer membrane
B) Gram-negative bacteria have a thick peptidoglycan layer
C) Gram-positive bacteria have teichoic acids in their cell wall
D) Gram-negative bacteria lack lipopolysaccharide
Answer: C) Gram-positive bacteria have teichoic acids in their cell wall
Teichoic acids are unique to Gram-positive cell walls and are not found in Gram-
negative bacteria. Gram-positive bacteria have a thick peptidoglycan layer, while
Gram-negative bacteria have a thin peptidoglycan layer surrounded by an outer
membrane containing lipopolysaccharide (LPS) .
Question 8
Which of the following describes the cell wall structure of Gram-positive bacteria?
A) Thin layer of peptidoglycan with an outer membrane containing LPS
B) Thick layer of peptidoglycan with teichoic acids
C) No peptidoglycan, composed of pseudopeptidoglycan
D) Outer membrane of lipoteichoic acid
Answer: B) Thick layer of peptidoglycan with teichoic acids
*Gram-positive bacteria have a thick (20-80 nm) peptidoglycan layer that retains
the crystal violet stain. Teichoic acids (including lipoteichoic acid) are embedded
in the peptidoglycan and contribute to cell wall structure and adhesion .*
