StraighterLine Microbiology BIO250 Final
Proctored Exam Review 2026/2027: Actual
Exam Questions with Verified Answers –
Complete Study Guide – Graded A+
SECTION 1: HISTORY, TAXONOMY, AND MICROBIAL DIVERSITY (Questions
1-5)
Q1: Which scientist definitively disproved spontaneous generation through the use of
swan-neck flasks, demonstrating that microorganisms come from pre-existing life
rather than arising de novo?
A. Francesco Redi
B. John Needham
C. Louis Pasteur
D. Lazzaro Spallanzani
Correct Answer: C
Rationale: Louis Pasteur (1861) used swan-neck flasks to definitively disprove
spontaneous generation. The curved necks allowed air to enter but trapped airborne
microorganisms in the bend, keeping the broth sterile indefinitely. When the necks were
broken, contamination occurred. Francesco Redi (A) disproved spontaneous generation
for maggots in meat (1668) but didn't use flasks. John Needham (B) actually supported
spontaneous generation with flawed experiments. Lazzaro Spallanzani (D) performed
,similar experiments with sealed flasks but was criticized for excluding "vital air," making
Pasteur's design superior. Pasteur's work established the germ theory of disease and
biogenesis (life from life).
(Topic: History of Microbiology | Difficulty: Easy)
Q2: According to the three-domain classification system proposed by Carl Woese, which
characteristic was used to distinguish Archaea from Bacteria and establish them as a
separate domain?
A. Presence of peptidoglycan in cell walls
B. Analysis of ribosomal RNA (rRNA) sequences
C. Presence of membrane-bound organelles
D. Ability to perform photosynthesis
Correct Answer: B
Rationale: Carl Woese and George Fox (1977) used 16S ribosomal RNA sequencing to
reveal that prokaryotes comprise two distinct evolutionary lineages: Bacteria and
Archaea. This molecular phylogenetic approach showed Archaea share features with
both Bacteria (prokaryotic cell structure) and Eukarya (similar RNA polymerases,
histone-like proteins, no peptidoglycan). Option A is incorrect because Archaea lack
peptidoglycan (a bacterial feature). Option C is incorrect as neither Bacteria nor Archaea
have membrane-bound organelles (both are prokaryotes). Option D is incorrect because
photosynthesis occurs in both domains. Woese's work revolutionized taxonomy by
replacing the five-kingdom system with the three-domain system (Bacteria, Archaea,
Eukarya).
,(Topic: Taxonomy & Classification | Difficulty: Easy)
Q3: Which of the following scientists is correctly matched with their contribution?
(Select all that apply)
A. Robert Koch – Developed pure culture techniques and formulated postulates for
establishing causative agents of disease
B. Joseph Lister – Introduced antiseptic surgery using phenol to reduce surgical
infections
C. Alexander Fleming – Discovered the first antibiotic, penicillin, from Penicillium mold
D. Edward Jenner – Developed the smallpox vaccine using cowpox inoculation
E. Hans Christian Gram – Developed the Gram stain to differentiate bacteria based on
cell wall properties
F. Antonie van Leeuwenhoek – Developed the first compound microscope and observed
animalcules
Correct Answer: A, B, C, D, E
Rationale: All five scientists are correctly matched. Robert Koch (A) developed solid
media using agar (with Fannie Hesse's suggestion) and established Koch's postulates.
Joseph Lister (B) applied Pasteur's germ theory to surgery in 1867, using carbolic acid
(phenol) sprays. Alexander Fleming (C) discovered penicillin in 1928 when Penicillium
mold contaminated a Staphylococcus plate. Edward Jenner (D) developed vaccination
in 1796 using cowpox to protect against smallpox. Hans Christian Gram (E) developed
the differential staining technique in 1884. Option F is incorrect because Leeuwenhoek
, used simple microscopes (single lenses), not compound microscopes, to observe
"animalcules" in 1676.
(Topic: Historical Figures | Difficulty: Easy)
Q4: The taxonomic hierarchy from broadest to most specific is: Domain, _______,
Phylum, Class, Order, Family, Genus, Species.
Correct Answer: Kingdom
Rationale: The complete taxonomic hierarchy is: Domain → Kingdom → Phylum →
Class → Order → Family → Genus → Species. This eight-tier system reflects the
evolutionary relationships among organisms. The three domains (Bacteria, Archaea,
Eukarya) represent the highest level of classification based on cellular organization and
molecular phylogeny. Within each domain, organisms are further subdivided into
kingdoms (e.g., in Eukarya: Animalia, Plantae, Fungi, Protista). The mnemonic "Dear
King Philip Came Over For Good Soup" or "Do Kings Play Chess On Fine Green Silk"
helps remember this sequence. Carl Linnaeus established the binomial nomenclature
system (Genus species) in the 18th century, while the domain level was added by
Woese in 1977.
(Topic: Taxonomy | Difficulty: Easy)
Q5: Which group of organisms lacks peptidoglycan in their cell walls and includes many
extremophiles capable of thriving in extreme temperatures, salinity, or pH?
A. Bacteria
B. Archaea
C. Eukarya
Proctored Exam Review 2026/2027: Actual
Exam Questions with Verified Answers –
Complete Study Guide – Graded A+
SECTION 1: HISTORY, TAXONOMY, AND MICROBIAL DIVERSITY (Questions
1-5)
Q1: Which scientist definitively disproved spontaneous generation through the use of
swan-neck flasks, demonstrating that microorganisms come from pre-existing life
rather than arising de novo?
A. Francesco Redi
B. John Needham
C. Louis Pasteur
D. Lazzaro Spallanzani
Correct Answer: C
Rationale: Louis Pasteur (1861) used swan-neck flasks to definitively disprove
spontaneous generation. The curved necks allowed air to enter but trapped airborne
microorganisms in the bend, keeping the broth sterile indefinitely. When the necks were
broken, contamination occurred. Francesco Redi (A) disproved spontaneous generation
for maggots in meat (1668) but didn't use flasks. John Needham (B) actually supported
spontaneous generation with flawed experiments. Lazzaro Spallanzani (D) performed
,similar experiments with sealed flasks but was criticized for excluding "vital air," making
Pasteur's design superior. Pasteur's work established the germ theory of disease and
biogenesis (life from life).
(Topic: History of Microbiology | Difficulty: Easy)
Q2: According to the three-domain classification system proposed by Carl Woese, which
characteristic was used to distinguish Archaea from Bacteria and establish them as a
separate domain?
A. Presence of peptidoglycan in cell walls
B. Analysis of ribosomal RNA (rRNA) sequences
C. Presence of membrane-bound organelles
D. Ability to perform photosynthesis
Correct Answer: B
Rationale: Carl Woese and George Fox (1977) used 16S ribosomal RNA sequencing to
reveal that prokaryotes comprise two distinct evolutionary lineages: Bacteria and
Archaea. This molecular phylogenetic approach showed Archaea share features with
both Bacteria (prokaryotic cell structure) and Eukarya (similar RNA polymerases,
histone-like proteins, no peptidoglycan). Option A is incorrect because Archaea lack
peptidoglycan (a bacterial feature). Option C is incorrect as neither Bacteria nor Archaea
have membrane-bound organelles (both are prokaryotes). Option D is incorrect because
photosynthesis occurs in both domains. Woese's work revolutionized taxonomy by
replacing the five-kingdom system with the three-domain system (Bacteria, Archaea,
Eukarya).
,(Topic: Taxonomy & Classification | Difficulty: Easy)
Q3: Which of the following scientists is correctly matched with their contribution?
(Select all that apply)
A. Robert Koch – Developed pure culture techniques and formulated postulates for
establishing causative agents of disease
B. Joseph Lister – Introduced antiseptic surgery using phenol to reduce surgical
infections
C. Alexander Fleming – Discovered the first antibiotic, penicillin, from Penicillium mold
D. Edward Jenner – Developed the smallpox vaccine using cowpox inoculation
E. Hans Christian Gram – Developed the Gram stain to differentiate bacteria based on
cell wall properties
F. Antonie van Leeuwenhoek – Developed the first compound microscope and observed
animalcules
Correct Answer: A, B, C, D, E
Rationale: All five scientists are correctly matched. Robert Koch (A) developed solid
media using agar (with Fannie Hesse's suggestion) and established Koch's postulates.
Joseph Lister (B) applied Pasteur's germ theory to surgery in 1867, using carbolic acid
(phenol) sprays. Alexander Fleming (C) discovered penicillin in 1928 when Penicillium
mold contaminated a Staphylococcus plate. Edward Jenner (D) developed vaccination
in 1796 using cowpox to protect against smallpox. Hans Christian Gram (E) developed
the differential staining technique in 1884. Option F is incorrect because Leeuwenhoek
, used simple microscopes (single lenses), not compound microscopes, to observe
"animalcules" in 1676.
(Topic: Historical Figures | Difficulty: Easy)
Q4: The taxonomic hierarchy from broadest to most specific is: Domain, _______,
Phylum, Class, Order, Family, Genus, Species.
Correct Answer: Kingdom
Rationale: The complete taxonomic hierarchy is: Domain → Kingdom → Phylum →
Class → Order → Family → Genus → Species. This eight-tier system reflects the
evolutionary relationships among organisms. The three domains (Bacteria, Archaea,
Eukarya) represent the highest level of classification based on cellular organization and
molecular phylogeny. Within each domain, organisms are further subdivided into
kingdoms (e.g., in Eukarya: Animalia, Plantae, Fungi, Protista). The mnemonic "Dear
King Philip Came Over For Good Soup" or "Do Kings Play Chess On Fine Green Silk"
helps remember this sequence. Carl Linnaeus established the binomial nomenclature
system (Genus species) in the 18th century, while the domain level was added by
Woese in 1977.
(Topic: Taxonomy | Difficulty: Easy)
Q5: Which group of organisms lacks peptidoglycan in their cell walls and includes many
extremophiles capable of thriving in extreme temperatures, salinity, or pH?
A. Bacteria
B. Archaea
C. Eukarya
