WGU D311 OA Final Exam Version 2 /
WGU D311 Microbiology Objective
Assessment Final Exam Newest
2025/2026 Actual Exam Complete 100
Questions And Correct Detailed
Answers (Verified Answers) |Already
Graded A+||Brand New Version!!
Question 1
Q: Which domain includes microorganisms that lack a nucleus
and have peptidoglycan in their cell walls?
A) Eukarya
B) Archaea
C) Bacteria
D) Protista
A: C) Bacteria
Rationale: Bacteria are prokaryotic (no nucleus) and have cell
walls containing peptidoglycan. Archaea lack peptidoglycan;
Eukarya have a nucleus.
,Question 2
Q: What is the primary function of the bacterial ribosome?
A) DNA replication
B) Protein synthesis
C) ATP production
D) Motility
A: B) Protein synthesis
Rationale: Ribosomes (70S in bacteria) translate mRNA into
polypeptides. DNA replication occurs in the nucleoid; ATP
production occurs on the plasma membrane.
Question 3
Q: Which structure is responsible for genetic exchange via
conjugation?
A) Flagellum
B) Pilus (sex pilus)
C) Capsule
D) Endospore
A: B) Pilus (sex pilus)
Rationale: The sex pilus forms a bridge between bacteria for
transfer of plasmid DNA (conjugation). Flagella = motility; capsule
= protection; endospore = survival.
,Question 4
Q: A Gram stain shows purple cocci in clusters. What is the likely
identification?
A) Escherichia coli (Gram-negative rods)
B) Staphylococcus aureus (Gram-positive cocci in clusters)
C) Streptococcus pyogenes (Gram-positive cocci in chains)
D) Neisseria gonorrhoeae (Gram-negative diplococci)
A: B) Staphylococcus aureus
Rationale: Purple = Gram-positive. Cocci in clusters
= Staphylococcus. Chains would be Streptococcus.
Question 5
Q: Which bacterial structure is an endotoxin?
A) Teichoic acid
B) Lipopolysaccharide (LPS)
C) Exotoxin A
D) Flagellin
A: B) Lipopolysaccharide (LPS)
Rationale: LPS is embedded in the outer membrane of Gram-
negative bacteria and is released upon lysis, causing fever, shock,
and inflammation (endotoxin activity).
, Question 6
Q: A microbe grows at 55°C. This is a:
A) Psychrophile
B) Mesophile
C) Thermophile
D) Hyperthermophile
A: C) Thermophile
Rationale: Psychrophile (<15°C), Mesophile (20–40°C),
Thermophile (45–80°C), Hyperthermophile (>80°C). 55°C is
thermophilic.
Question 7
Q: Which is a catabolic process?
A) Gluconeogenesis
B) Lipid synthesis
C) Cellular respiration
D) DNA replication
A: C) Cellular respiration
Rationale: Catabolism = breaking down molecules to release
energy. Cellular respiration breaks down glucose into CO₂ + H₂O
+ ATP.
WGU D311 Microbiology Objective
Assessment Final Exam Newest
2025/2026 Actual Exam Complete 100
Questions And Correct Detailed
Answers (Verified Answers) |Already
Graded A+||Brand New Version!!
Question 1
Q: Which domain includes microorganisms that lack a nucleus
and have peptidoglycan in their cell walls?
A) Eukarya
B) Archaea
C) Bacteria
D) Protista
A: C) Bacteria
Rationale: Bacteria are prokaryotic (no nucleus) and have cell
walls containing peptidoglycan. Archaea lack peptidoglycan;
Eukarya have a nucleus.
,Question 2
Q: What is the primary function of the bacterial ribosome?
A) DNA replication
B) Protein synthesis
C) ATP production
D) Motility
A: B) Protein synthesis
Rationale: Ribosomes (70S in bacteria) translate mRNA into
polypeptides. DNA replication occurs in the nucleoid; ATP
production occurs on the plasma membrane.
Question 3
Q: Which structure is responsible for genetic exchange via
conjugation?
A) Flagellum
B) Pilus (sex pilus)
C) Capsule
D) Endospore
A: B) Pilus (sex pilus)
Rationale: The sex pilus forms a bridge between bacteria for
transfer of plasmid DNA (conjugation). Flagella = motility; capsule
= protection; endospore = survival.
,Question 4
Q: A Gram stain shows purple cocci in clusters. What is the likely
identification?
A) Escherichia coli (Gram-negative rods)
B) Staphylococcus aureus (Gram-positive cocci in clusters)
C) Streptococcus pyogenes (Gram-positive cocci in chains)
D) Neisseria gonorrhoeae (Gram-negative diplococci)
A: B) Staphylococcus aureus
Rationale: Purple = Gram-positive. Cocci in clusters
= Staphylococcus. Chains would be Streptococcus.
Question 5
Q: Which bacterial structure is an endotoxin?
A) Teichoic acid
B) Lipopolysaccharide (LPS)
C) Exotoxin A
D) Flagellin
A: B) Lipopolysaccharide (LPS)
Rationale: LPS is embedded in the outer membrane of Gram-
negative bacteria and is released upon lysis, causing fever, shock,
and inflammation (endotoxin activity).
, Question 6
Q: A microbe grows at 55°C. This is a:
A) Psychrophile
B) Mesophile
C) Thermophile
D) Hyperthermophile
A: C) Thermophile
Rationale: Psychrophile (<15°C), Mesophile (20–40°C),
Thermophile (45–80°C), Hyperthermophile (>80°C). 55°C is
thermophilic.
Question 7
Q: Which is a catabolic process?
A) Gluconeogenesis
B) Lipid synthesis
C) Cellular respiration
D) DNA replication
A: C) Cellular respiration
Rationale: Catabolism = breaking down molecules to release
energy. Cellular respiration breaks down glucose into CO₂ + H₂O
+ ATP.
