WGU D311 Microbiology OA Exam – Complete Study Guide & 250
Practice Questions (2026)
Section 1: Microbial World & Cell Structure (Questions 1–30)
1. 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 prokaryotic cells that lack a true nucleus and
membrane-bound organelles.
,2. Which statement accurately describes prokaryotic cells?
A) They have multiple rod-shaped chromosomes.
B) They are found in coccus form in both pairs and clusters.
C) They have a nucleus surrounded by a complex nuclear membrane.
D) They are found only as single cells.
Answer B: ) They are found in coccus form in both pairs and clusters.
Rationale: Prokaryotic cells are single-celled, lack a nucleus, and can
form various arrangements including pairs (diplococci) and clusters
(staphylococci).
3. Which characteristic distinguishes eukaryotic cells from
prokaryotic cells?
A) They have a nucleus surrounded by a complex nuclear membrane.
B) They lack membrane-bound organelles.
C) They are smaller in size.
D) They reproduce by binary fission.
Answer A: ) Eukaryotic cells have a nucleus surrounded by a
complex nuclear membrane.
,Rationale: Eukaryotic cells contain a true nucleus enclosed by a
nuclear membrane, along with membrane-bound organelles such as
mitochondria and endoplasmic reticulum.
4. Which component is found specifically in the cell walls of bacteria
but not in archaea or eukaryotes?
A) Phospholipids
B) Chitin
C) Peptidoglycan
D) Cellulose
Answer C: ) Peptidoglycan
Rationale: Peptidoglycan is a unique polymer consisting of sugars and
amino acids that forms a mesh-like layer outside the plasma
membrane of most bacteria.
5. What is the significance of microorganisms containing a thick coat
of peptidoglycan within the cell wall?
A) They are typically classified as Gram-positive bacteria.
B) They are classified as Gram-negative bacteria.
, C) They are resistant to all antibiotics.
D) They lack a cell wall.
Answer A: ) They are typically classified as Gram-positive bacteria.
Rationale: Gram-positive bacteria have a thick, multilayered cell wall
composed primarily of peptidoglycan (60-90% of the wall) along with
teichoic acids.
6. Which component is found in the outer membrane of Gram-
negative bacteria?
A) Teichoic acid
B) Lipopolysaccharide (LPS)
C) Peptidoglycan only
D) Mycolic acid
Answer B: ) Lipopolysaccharide (LPS)
Rationale: LPS is found in the outer membrane of Gram-negative
bacteria and acts as an endotoxin.
7. What is the primary function of the bacterial capsule?
A) Protein synthesis
Practice Questions (2026)
Section 1: Microbial World & Cell Structure (Questions 1–30)
1. 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 prokaryotic cells that lack a true nucleus and
membrane-bound organelles.
,2. Which statement accurately describes prokaryotic cells?
A) They have multiple rod-shaped chromosomes.
B) They are found in coccus form in both pairs and clusters.
C) They have a nucleus surrounded by a complex nuclear membrane.
D) They are found only as single cells.
Answer B: ) They are found in coccus form in both pairs and clusters.
Rationale: Prokaryotic cells are single-celled, lack a nucleus, and can
form various arrangements including pairs (diplococci) and clusters
(staphylococci).
3. Which characteristic distinguishes eukaryotic cells from
prokaryotic cells?
A) They have a nucleus surrounded by a complex nuclear membrane.
B) They lack membrane-bound organelles.
C) They are smaller in size.
D) They reproduce by binary fission.
Answer A: ) Eukaryotic cells have a nucleus surrounded by a
complex nuclear membrane.
,Rationale: Eukaryotic cells contain a true nucleus enclosed by a
nuclear membrane, along with membrane-bound organelles such as
mitochondria and endoplasmic reticulum.
4. Which component is found specifically in the cell walls of bacteria
but not in archaea or eukaryotes?
A) Phospholipids
B) Chitin
C) Peptidoglycan
D) Cellulose
Answer C: ) Peptidoglycan
Rationale: Peptidoglycan is a unique polymer consisting of sugars and
amino acids that forms a mesh-like layer outside the plasma
membrane of most bacteria.
5. What is the significance of microorganisms containing a thick coat
of peptidoglycan within the cell wall?
A) They are typically classified as Gram-positive bacteria.
B) They are classified as Gram-negative bacteria.
, C) They are resistant to all antibiotics.
D) They lack a cell wall.
Answer A: ) They are typically classified as Gram-positive bacteria.
Rationale: Gram-positive bacteria have a thick, multilayered cell wall
composed primarily of peptidoglycan (60-90% of the wall) along with
teichoic acids.
6. Which component is found in the outer membrane of Gram-
negative bacteria?
A) Teichoic acid
B) Lipopolysaccharide (LPS)
C) Peptidoglycan only
D) Mycolic acid
Answer B: ) Lipopolysaccharide (LPS)
Rationale: LPS is found in the outer membrane of Gram-negative
bacteria and acts as an endotoxin.
7. What is the primary function of the bacterial capsule?
A) Protein synthesis
