OpenStax Microbiology Test Bank / OSX
Microbiology Test Bank - Chapter 01 to Chapter
05 (Multiple Choice, True/False, Matching, Fill in
the Blank, Short Answers & Brief Essay) 2026
Question 1: Which of the following individuals is credited as the first person to
observe live, microscopic "animalcules" using a single-lens microscope he
constructed himself?
• A. Robert Hooke
• B. Louis Pasteur
• C. Antonie van Leeuwenhoek
• D. Robert Koch
• Correct Answer: C. Antonie van Leeuwenhoek
• Rationale: While Robert Hooke first observed dead plant cells in cork,
Antonie van Leeuwenhoek was the first to view and describe live moving
microorganisms (bacteria and protozoa) in the late 17th century using his
highly refined lenses.
Question 2: In the binomial nomenclature system established by Carl Linnaeus,
which of the following represents the correct format for writing a microbial name?
• A. escherichia Coli
• B. Escherichia coli
• C. Escherichia coli
• D. Escherichia Coli
• Correct Answer: B. Escherichia coli
• Rationale: Binomial nomenclature requires that the genus name be
capitalized, the specific epithet (species name) be lowercase, and the entire
scientific name be italicized (or underlined if handwritten).
,Question 3: Which of the following domains of life contain prokaryotic organisms
lacking a membrane-bound nucleus?
• A. Bacteria only
• B. Archaea only
• C. Bacteria and Archaea
• D. Archaea and Eukarya
• Correct Answer: C. Bacteria and Archaea
• Rationale: Both Bacteria and Archaea are cellular prokaryotes that lack a
true nucleus and membrane-bound organelles. Eukarya comprises all
eukaryotic organisms.
Question 4: A microscopic, single-celled eukaryote that moves via pseudopods,
cilia, or flagella and lacks a cell wall is best classified as a(n):
• A. Bacterium
• B. Alga
• C. Fungus
• D. Protozoan
• Correct Answer: D. Protozoan
• Rationale: Protozoa are non-photosynthetic, motile, unicellular eukaryotes
that lack rigid cell walls, distinguishing them from algae (photosynthetic)
and fungi (have chitin cell walls).
Question 5: Viruses are classified as acellular infectious agents. This status is
primarily because they:
• A. Lack cellular structures such as a plasma membrane and metabolic
machinery, requiring a host cell to replicate.
• B. Do not contain genetic material.
• C. Are always smaller than 10 nanometers.
• D. Possess cell walls made of peptidoglycan.
, • Correct Answer: A. Lack cellular structures such as a plasma
membrane and metabolic machinery, requiring a host cell to replicate.
• Rationale: Viruses are obligate intracellular parasites composed simply of a
nucleic acid core (DNA or RNA) enclosed within a protein coat (capsid).
They carry out no independent metabolism.
True or False
Question 6: Archaea are known to possess cell walls composed of a unique
polymer called peptidoglycan.
• Correct Answer: False
• Rationale: Archaea lack true peptidoglycan in their cell walls; instead, their
cell walls may be composed of pseudopeptidoglycan (pseudomurein),
glycoproteins, or polysaccharides. Peptidoglycan is unique to the domain
Bacteria.
Question 7: Algae are photosynthetic eukaryotic organisms that play a major role
in producing oxygen and organic compounds in aquatic environments.
• Correct Answer: True
• Rationale: Algae contain chloroplasts and carry out oxygenic
photosynthesis, making them essential primary producers in freshwater and
marine ecosystems.
Question 8: Molds and yeasts are both classified as fungi, but yeasts are
unicellular while molds are multicellular and filamentous.
• Correct Answer: True
• Rationale: This represents the fundamental morphological split within the
kingdom Fungi: yeasts grow as single cells that reproduce by budding,
whereas molds form networks of filaments called hyphae.
Question 9: The dynamic evolutionary tree of life proposed by Carl Woese and
George Fox uses differences in transfer RNA (tRNA) to sort organisms into three
distinct domains.
• Correct Answer: False
Microbiology Test Bank - Chapter 01 to Chapter
05 (Multiple Choice, True/False, Matching, Fill in
the Blank, Short Answers & Brief Essay) 2026
Question 1: Which of the following individuals is credited as the first person to
observe live, microscopic "animalcules" using a single-lens microscope he
constructed himself?
• A. Robert Hooke
• B. Louis Pasteur
• C. Antonie van Leeuwenhoek
• D. Robert Koch
• Correct Answer: C. Antonie van Leeuwenhoek
• Rationale: While Robert Hooke first observed dead plant cells in cork,
Antonie van Leeuwenhoek was the first to view and describe live moving
microorganisms (bacteria and protozoa) in the late 17th century using his
highly refined lenses.
Question 2: In the binomial nomenclature system established by Carl Linnaeus,
which of the following represents the correct format for writing a microbial name?
• A. escherichia Coli
• B. Escherichia coli
• C. Escherichia coli
• D. Escherichia Coli
• Correct Answer: B. Escherichia coli
• Rationale: Binomial nomenclature requires that the genus name be
capitalized, the specific epithet (species name) be lowercase, and the entire
scientific name be italicized (or underlined if handwritten).
,Question 3: Which of the following domains of life contain prokaryotic organisms
lacking a membrane-bound nucleus?
• A. Bacteria only
• B. Archaea only
• C. Bacteria and Archaea
• D. Archaea and Eukarya
• Correct Answer: C. Bacteria and Archaea
• Rationale: Both Bacteria and Archaea are cellular prokaryotes that lack a
true nucleus and membrane-bound organelles. Eukarya comprises all
eukaryotic organisms.
Question 4: A microscopic, single-celled eukaryote that moves via pseudopods,
cilia, or flagella and lacks a cell wall is best classified as a(n):
• A. Bacterium
• B. Alga
• C. Fungus
• D. Protozoan
• Correct Answer: D. Protozoan
• Rationale: Protozoa are non-photosynthetic, motile, unicellular eukaryotes
that lack rigid cell walls, distinguishing them from algae (photosynthetic)
and fungi (have chitin cell walls).
Question 5: Viruses are classified as acellular infectious agents. This status is
primarily because they:
• A. Lack cellular structures such as a plasma membrane and metabolic
machinery, requiring a host cell to replicate.
• B. Do not contain genetic material.
• C. Are always smaller than 10 nanometers.
• D. Possess cell walls made of peptidoglycan.
, • Correct Answer: A. Lack cellular structures such as a plasma
membrane and metabolic machinery, requiring a host cell to replicate.
• Rationale: Viruses are obligate intracellular parasites composed simply of a
nucleic acid core (DNA or RNA) enclosed within a protein coat (capsid).
They carry out no independent metabolism.
True or False
Question 6: Archaea are known to possess cell walls composed of a unique
polymer called peptidoglycan.
• Correct Answer: False
• Rationale: Archaea lack true peptidoglycan in their cell walls; instead, their
cell walls may be composed of pseudopeptidoglycan (pseudomurein),
glycoproteins, or polysaccharides. Peptidoglycan is unique to the domain
Bacteria.
Question 7: Algae are photosynthetic eukaryotic organisms that play a major role
in producing oxygen and organic compounds in aquatic environments.
• Correct Answer: True
• Rationale: Algae contain chloroplasts and carry out oxygenic
photosynthesis, making them essential primary producers in freshwater and
marine ecosystems.
Question 8: Molds and yeasts are both classified as fungi, but yeasts are
unicellular while molds are multicellular and filamentous.
• Correct Answer: True
• Rationale: This represents the fundamental morphological split within the
kingdom Fungi: yeasts grow as single cells that reproduce by budding,
whereas molds form networks of filaments called hyphae.
Question 9: The dynamic evolutionary tree of life proposed by Carl Woese and
George Fox uses differences in transfer RNA (tRNA) to sort organisms into three
distinct domains.
• Correct Answer: False
