LSU ENVS 2126 Test 1 — Lomnicki Questions
and Answers| 2027 Updated
LSU ENVS 2126 – Test 1 (Lomnicki)
Verified Questions & Answers (2027 Updated)
Course: ENVS 2126 – Microbiology (Louisiana State University)
Instructor: Lomnicki
SECTION 1: CELL STRUCTURE & FUNCTION
1. Eukaryotes have ________ in their cytoplasmic membranes, which serve to
strengthen and stabilize the membrane and make it less flexible. Many bacteria
have similar molecules, known as ________, in their cytoplasmic membranes
that have a similar role.
A. sterols / hopanoids
B. hopanoids / sterols
C. phospholipids / proteins
D. proteins / phospholipids
Correct Answer: A. sterols / hopanoids. Rationale: Eukaryotes have sterols in
their membranes, while bacteria have hopanoids that serve a similar stabilizing
function .
2. The cytoplasmic membrane could best be described as:
,A. A rigid, impermeable barrier
B. A highly selective permeability barrier
C. A completely permeable barrier
D. A non-functional layer
Correct Answer: B. A highly selective permeability barrier. Rationale: The
cytoplasmic membrane is a highly selective permeability barrier that controls what
enters and exits the cell .
3. Actin is found within ________.
A. prokaryotic flagella
B. eukaryotic microfilaments
C. bacterial cell walls
D. archaeal membranes
Correct Answer: B. eukaryotic microfilaments. Rationale: Actin is a protein found
in eukaryotic microfilaments and is involved in cell movement and structure .
4. The rigid layer that is present in the cell walls of Bacteria that is primarily
responsible for the strength of the wall is known as:
A. cellulose
B. chitin
C. peptidoglycan
D. lipopolysaccharide
Correct Answer: C. peptidoglycan. Rationale: Peptidoglycan is the rigid layer in
bacterial cell walls that provides structural strength .
5. Although the inner leaflet of the gram-negative outer membrane is composed
mainly of phospholipids, the outer leaflet of the outer membrane contains:
,A. peptidoglycan
B. lipopolysaccharides (LPS)
C. teichoic acids
D. cellulose
Correct Answer: B. lipopolysaccharides (LPS). Rationale: The outer leaflet of the
gram-negative outer membrane contains lipopolysaccharides (LPS), which act as
endotoxins .
6. Archaeans have archaella that rotate like bacterial flagella though they:
A. consist of a single protein type
B. consist of multiple protein types
C. do not rotate at all
D. are made of peptidoglycan
Correct Answer: B. consist of multiple protein types. Rationale: Archaella consist
of multiple protein types, unlike bacterial flagella which are made of a single
protein (flagellin) .
7. You have discovered a new coccoid-shaped microorganism with no nucleus, a
rigid cell wall, and a diameter of 2 μm. Chemical tests reveal that its cell wall
does NOT contain peptidoglycan. This organism is most likely a(n):
A. bacterium
B. archaeon
C. eukaryote
D. virus
Correct Answer: B. archaeon. Rationale: Archaea have no nucleus, rigid cell walls,
and lack peptidoglycan in their cell walls .
, 8. Which of the following is a function of the cytoplasmic membrane in
prokaryotes?
A. Permeability barrier only
B. Docking station for proteins involved in bioenergetics reactions and transport
C. Site for energy conservation
D. All of the above
Correct Answer: D. All of the above. Rationale: The cytoplasmic membrane serves
as a permeability barrier, a docking station for proteins involved in bioenergetics
reactions and transport, and a site for energy conservation .
9. Which of the following statements about bacterial flagella is true?
A. They cannot rotate
B. They can rotate 360 degrees
C. They are made of peptidoglycan
D. They are found only in gram-positive bacteria
Correct Answer: B. They can rotate 360 degrees. Rationale: Bacterial flagella can
rotate 360 degrees to propel the cell .
10. Taxis is:
A. movement towards or away from a stimulus
B. cell division
C. protein synthesis
D. DNA replication
Correct Answer: A. movement towards or away from a stimulus. Rationale: Taxis
is directed movement toward or away from a stimulus .
11. Which of the following terms refers to a bacterium moving towards a light
source?
and Answers| 2027 Updated
LSU ENVS 2126 – Test 1 (Lomnicki)
Verified Questions & Answers (2027 Updated)
Course: ENVS 2126 – Microbiology (Louisiana State University)
Instructor: Lomnicki
SECTION 1: CELL STRUCTURE & FUNCTION
1. Eukaryotes have ________ in their cytoplasmic membranes, which serve to
strengthen and stabilize the membrane and make it less flexible. Many bacteria
have similar molecules, known as ________, in their cytoplasmic membranes
that have a similar role.
A. sterols / hopanoids
B. hopanoids / sterols
C. phospholipids / proteins
D. proteins / phospholipids
Correct Answer: A. sterols / hopanoids. Rationale: Eukaryotes have sterols in
their membranes, while bacteria have hopanoids that serve a similar stabilizing
function .
2. The cytoplasmic membrane could best be described as:
,A. A rigid, impermeable barrier
B. A highly selective permeability barrier
C. A completely permeable barrier
D. A non-functional layer
Correct Answer: B. A highly selective permeability barrier. Rationale: The
cytoplasmic membrane is a highly selective permeability barrier that controls what
enters and exits the cell .
3. Actin is found within ________.
A. prokaryotic flagella
B. eukaryotic microfilaments
C. bacterial cell walls
D. archaeal membranes
Correct Answer: B. eukaryotic microfilaments. Rationale: Actin is a protein found
in eukaryotic microfilaments and is involved in cell movement and structure .
4. The rigid layer that is present in the cell walls of Bacteria that is primarily
responsible for the strength of the wall is known as:
A. cellulose
B. chitin
C. peptidoglycan
D. lipopolysaccharide
Correct Answer: C. peptidoglycan. Rationale: Peptidoglycan is the rigid layer in
bacterial cell walls that provides structural strength .
5. Although the inner leaflet of the gram-negative outer membrane is composed
mainly of phospholipids, the outer leaflet of the outer membrane contains:
,A. peptidoglycan
B. lipopolysaccharides (LPS)
C. teichoic acids
D. cellulose
Correct Answer: B. lipopolysaccharides (LPS). Rationale: The outer leaflet of the
gram-negative outer membrane contains lipopolysaccharides (LPS), which act as
endotoxins .
6. Archaeans have archaella that rotate like bacterial flagella though they:
A. consist of a single protein type
B. consist of multiple protein types
C. do not rotate at all
D. are made of peptidoglycan
Correct Answer: B. consist of multiple protein types. Rationale: Archaella consist
of multiple protein types, unlike bacterial flagella which are made of a single
protein (flagellin) .
7. You have discovered a new coccoid-shaped microorganism with no nucleus, a
rigid cell wall, and a diameter of 2 μm. Chemical tests reveal that its cell wall
does NOT contain peptidoglycan. This organism is most likely a(n):
A. bacterium
B. archaeon
C. eukaryote
D. virus
Correct Answer: B. archaeon. Rationale: Archaea have no nucleus, rigid cell walls,
and lack peptidoglycan in their cell walls .
, 8. Which of the following is a function of the cytoplasmic membrane in
prokaryotes?
A. Permeability barrier only
B. Docking station for proteins involved in bioenergetics reactions and transport
C. Site for energy conservation
D. All of the above
Correct Answer: D. All of the above. Rationale: The cytoplasmic membrane serves
as a permeability barrier, a docking station for proteins involved in bioenergetics
reactions and transport, and a site for energy conservation .
9. Which of the following statements about bacterial flagella is true?
A. They cannot rotate
B. They can rotate 360 degrees
C. They are made of peptidoglycan
D. They are found only in gram-positive bacteria
Correct Answer: B. They can rotate 360 degrees. Rationale: Bacterial flagella can
rotate 360 degrees to propel the cell .
10. Taxis is:
A. movement towards or away from a stimulus
B. cell division
C. protein synthesis
D. DNA replication
Correct Answer: A. movement towards or away from a stimulus. Rationale: Taxis
is directed movement toward or away from a stimulus .
11. Which of the following terms refers to a bacterium moving towards a light
source?
