BIOD 171
OBJECTIVE ASSESSMENT - EXAM
Microbiology BIOD 171 Final
Exam - Portage learning
2026/2027 Actual Exam
2026/2027
75 Microbiology
Essential 100% 2026/2027
QUESTIONS VERIFIED ANSWERS EDITION
TOPICS COVERED
Cell Structure and Function Antimicrobial Agents and Resistance
Microbial Metabolism and Energy Pathways Immunology and Host Defense
Microscopy and Staining Methods Viral Structure, Replication, and Disease
COVER PAGE - 1
, SECTION 1 | Fundamentals of Microbiology | Q1-Q15 | Microbiology BIOD 171 Final Exam - Portage learning 2026/2027 Actual Exa
Q1 Question 1 of 75
A 34-year-old laboratory technician is reviewing the cellular structure of a newly
isolated soil bacterium. She notes the organism lacks membrane-bound organelles
and has a cell wall composed of peptidoglycan. When comparing this organism to a
human cheek epithelial cell, which structural feature would be found in the bacterial
cell but NOT in the human cell?
A. Ribosomes involved in protein synthesis
B. A cell membrane composed of a phospholipid bilayer
C. A capsule surrounding the cell wall
D. DNA as the genetic material
Correct Answer: C
Rationale:
Bacterial cells possess a capsule, an outer polysaccharide layer that aids in virulence and evasion of
phagocytosis. Human epithelial cells are eukaryotic and lack capsules. Both cell types contain ribosomes,
phospholipid bilayer membranes, and DNA as genetic material.
Q2 Question 2 of 75
During a microbiology lecture, a professor explains that the lipid composition of
bacterial cell membranes differs significantly from eukaryotic membranes. Which lipid
component is characteristically found in the membranes of Archaea but is generally
absent from Bacteria and Eukarya?
A. Phospholipids with ester-linked fatty acid tails
B. Cholesterol embedded within the membrane
C. Phospholipids with ether-linked isoprenoid chains
D. Glycerol as the backbone of membrane lipids
Correct Answer: C
Rationale:
Archaeal membranes contain ether-linked isoprenoid chains rather than ester-linked fatty acids, which is a
key distinguishing feature. Bacteria and Eukarya both use ester-linked fatty acids. Cholesterol is found in
eukaryotes, and glycerol is common to all three domains.
, Q3 Question 3 of 75
A clinical microbiologist is examining a Gram-stained smear from a patient with
pneumonia. She observes purple, spherical cells arranged in grape-like clusters.
Based on these morphological characteristics, which genus is most likely responsible
for the infection?
C. Neisseria
D. Bacillus
A. Streptococcus
B. Staphylococcus
Correct Answer: D
Rationale:
Staphylococcus species are Gram-positive cocci that characteristically arrange in grape-like clusters.
Streptococcus forms chains, Neisseria are Gram-negative diplococci, and Bacillus are Gram-positive rods.
The purple color indicates Gram-positive status.
Q4 Question 4 of 75
In a research study on extremophiles, scientists isolate a microbe from a hot spring
with a pH of 2.5 and a temperature of 85 degrees C. The organism is found to thrive in
these harsh conditions. Which structural adaptation most likely contributes to this
organism's ability to survive at such high temperatures?
A. A cell wall rich in teichoic acids
B. Membrane lipids with saturated fatty acid chains
C. Presence of histone-like proteins stabilizing DNA
D. A periplasmic space containing digestive enzymes
Correct Answer: C
Rationale:
Hyperthermophiles often possess histone-like proteins that stabilize DNA against thermal denaturation.
Saturated fatty acids increase membrane rigidity but do not specifically address high-temperature DNA
stability. Teichoic acids and periplasmic spaces are not primary heat-resistance adaptations.
Q5 Question 5 of 75
Microbiology BIOD 171 Final Exam – Portage learning 2026/2027 Actual Exam 2026/2027 — 2026/2027 | Passing Score: 80% | Page 2 of 38
, A student is preparing a presentation on bacterial cell wall structure. She explains
that after treatment with lysozyme, a Gram-positive bacterium loses its cell wall and
becomes a spherical structure. What is the correct term for this wall-less bacterial
form, and in what environment would it typically be found?
A. Protoplast; found in isotonic media
B. Spheroplast; found in hypotonic media
C. Protoplast; found in hypertonic media
D. L-form; found in any osmotic condition
Correct Answer: A
Rationale:
A protoplast is a Gram-positive bacterium that has lost its cell wall and retains only the cytoplasmic
membrane. Protoplasts require isotonic or hypertonic conditions to prevent osmotic lysis. Spheroplasts
derive from Gram-negative bacteria, and L-forms can survive without a cell wall in various conditions.
Q6 Question 6 of 75
During a bacterial genetics lab, students observe that a culture of E. coli exposed to
UV light shows increased mutation rates. Which cellular component is most directly
damaged by UV radiation, leading to these mutations?
A. The peptidoglycan cell wall
B. The 70S ribosomal subunits
C. Thymine bases in DNA forming pyrimidine dimers
D. The lipid bilayer of the cell membrane
Correct Answer: C
Rationale:
UV radiation causes adjacent thymine bases in DNA to form covalent pyrimidine dimers, distorting the DNA
helix and leading to mutations during replication. Peptidoglycan, ribosomes, and membrane lipids are not the
primary targets of UV-induced mutagenesis.
Q7 Question 7 of 75
A microbiology instructor asks students to identify which cellular structure is
responsible for bacterial motility in aqueous environments. A student correctly
identifies a long, whip-like appendage. Which statement accurately describes the
energy source and mechanism of this structure?
Microbiology BIOD 171 Final Exam – Portage learning 2026/2027 Actual Exam 2026/2027 — 2026/2027 | Passing Score: 80% | Page 3 of 38
OBJECTIVE ASSESSMENT - EXAM
Microbiology BIOD 171 Final
Exam - Portage learning
2026/2027 Actual Exam
2026/2027
75 Microbiology
Essential 100% 2026/2027
QUESTIONS VERIFIED ANSWERS EDITION
TOPICS COVERED
Cell Structure and Function Antimicrobial Agents and Resistance
Microbial Metabolism and Energy Pathways Immunology and Host Defense
Microscopy and Staining Methods Viral Structure, Replication, and Disease
COVER PAGE - 1
, SECTION 1 | Fundamentals of Microbiology | Q1-Q15 | Microbiology BIOD 171 Final Exam - Portage learning 2026/2027 Actual Exa
Q1 Question 1 of 75
A 34-year-old laboratory technician is reviewing the cellular structure of a newly
isolated soil bacterium. She notes the organism lacks membrane-bound organelles
and has a cell wall composed of peptidoglycan. When comparing this organism to a
human cheek epithelial cell, which structural feature would be found in the bacterial
cell but NOT in the human cell?
A. Ribosomes involved in protein synthesis
B. A cell membrane composed of a phospholipid bilayer
C. A capsule surrounding the cell wall
D. DNA as the genetic material
Correct Answer: C
Rationale:
Bacterial cells possess a capsule, an outer polysaccharide layer that aids in virulence and evasion of
phagocytosis. Human epithelial cells are eukaryotic and lack capsules. Both cell types contain ribosomes,
phospholipid bilayer membranes, and DNA as genetic material.
Q2 Question 2 of 75
During a microbiology lecture, a professor explains that the lipid composition of
bacterial cell membranes differs significantly from eukaryotic membranes. Which lipid
component is characteristically found in the membranes of Archaea but is generally
absent from Bacteria and Eukarya?
A. Phospholipids with ester-linked fatty acid tails
B. Cholesterol embedded within the membrane
C. Phospholipids with ether-linked isoprenoid chains
D. Glycerol as the backbone of membrane lipids
Correct Answer: C
Rationale:
Archaeal membranes contain ether-linked isoprenoid chains rather than ester-linked fatty acids, which is a
key distinguishing feature. Bacteria and Eukarya both use ester-linked fatty acids. Cholesterol is found in
eukaryotes, and glycerol is common to all three domains.
, Q3 Question 3 of 75
A clinical microbiologist is examining a Gram-stained smear from a patient with
pneumonia. She observes purple, spherical cells arranged in grape-like clusters.
Based on these morphological characteristics, which genus is most likely responsible
for the infection?
C. Neisseria
D. Bacillus
A. Streptococcus
B. Staphylococcus
Correct Answer: D
Rationale:
Staphylococcus species are Gram-positive cocci that characteristically arrange in grape-like clusters.
Streptococcus forms chains, Neisseria are Gram-negative diplococci, and Bacillus are Gram-positive rods.
The purple color indicates Gram-positive status.
Q4 Question 4 of 75
In a research study on extremophiles, scientists isolate a microbe from a hot spring
with a pH of 2.5 and a temperature of 85 degrees C. The organism is found to thrive in
these harsh conditions. Which structural adaptation most likely contributes to this
organism's ability to survive at such high temperatures?
A. A cell wall rich in teichoic acids
B. Membrane lipids with saturated fatty acid chains
C. Presence of histone-like proteins stabilizing DNA
D. A periplasmic space containing digestive enzymes
Correct Answer: C
Rationale:
Hyperthermophiles often possess histone-like proteins that stabilize DNA against thermal denaturation.
Saturated fatty acids increase membrane rigidity but do not specifically address high-temperature DNA
stability. Teichoic acids and periplasmic spaces are not primary heat-resistance adaptations.
Q5 Question 5 of 75
Microbiology BIOD 171 Final Exam – Portage learning 2026/2027 Actual Exam 2026/2027 — 2026/2027 | Passing Score: 80% | Page 2 of 38
, A student is preparing a presentation on bacterial cell wall structure. She explains
that after treatment with lysozyme, a Gram-positive bacterium loses its cell wall and
becomes a spherical structure. What is the correct term for this wall-less bacterial
form, and in what environment would it typically be found?
A. Protoplast; found in isotonic media
B. Spheroplast; found in hypotonic media
C. Protoplast; found in hypertonic media
D. L-form; found in any osmotic condition
Correct Answer: A
Rationale:
A protoplast is a Gram-positive bacterium that has lost its cell wall and retains only the cytoplasmic
membrane. Protoplasts require isotonic or hypertonic conditions to prevent osmotic lysis. Spheroplasts
derive from Gram-negative bacteria, and L-forms can survive without a cell wall in various conditions.
Q6 Question 6 of 75
During a bacterial genetics lab, students observe that a culture of E. coli exposed to
UV light shows increased mutation rates. Which cellular component is most directly
damaged by UV radiation, leading to these mutations?
A. The peptidoglycan cell wall
B. The 70S ribosomal subunits
C. Thymine bases in DNA forming pyrimidine dimers
D. The lipid bilayer of the cell membrane
Correct Answer: C
Rationale:
UV radiation causes adjacent thymine bases in DNA to form covalent pyrimidine dimers, distorting the DNA
helix and leading to mutations during replication. Peptidoglycan, ribosomes, and membrane lipids are not the
primary targets of UV-induced mutagenesis.
Q7 Question 7 of 75
A microbiology instructor asks students to identify which cellular structure is
responsible for bacterial motility in aqueous environments. A student correctly
identifies a long, whip-like appendage. Which statement accurately describes the
energy source and mechanism of this structure?
Microbiology BIOD 171 Final Exam – Portage learning 2026/2027 Actual Exam 2026/2027 — 2026/2027 | Passing Score: 80% | Page 3 of 38
