Openstax Microbiology test bank practice complete
exam questions and answers
CHAPTER 1: AN INVISIBLE WORLD
Question 1
Which of the following is true of the microbial world?
A. All microbes are harmful.
B. Humans could survive without microbes.
C. Many microbes are helpful.
D. Most microbes are pathogenic.
Answer: C
Rationale: The vast majority of microbes are either harmless or beneficial to
humans. Only a small fraction of microorganisms are pathogenic. Microbes play
essential roles in nutrient cycling, digestion, and many industrial processes .
Question 2
When did humans first suspect the existence of microbes?
A. During the Industrial Revolution
B. In prehistoric times
C. In the last century
D. Within the last 500 years
Answer: B
Rationale: Ancient texts and practices suggest that humans suspected the
existence of invisible agents of disease and decay in prehistoric times, long before
microbes were directly observed .
,Question 3
Who first observed unicellular organisms, which he called "animalcules," using a
microscope he developed?
A. Robert Koch
B. Louis Pasteur
C. Thucydides
D. Antonie van Leeuwenhoek
Answer: D
Rationale: Antonie van Leeuwenhoek is credited with the first observation of
unicellular organisms, which he called "animalcules," using a single-lens
microscope of his own design .
Question 4
To reduce the risk of open flame from Bunsen burners, microbiologists are
increasingly using which device for easy, rapid benchtop sterilization of small
pieces of equipment?
A. Autoclaves
B. Ethylene oxide
C. Incubators
D. Microincinerators
Answer: D
Rationale: Microincinerators are increasingly used to reduce the risk of open
flames. They provide a flameless, benchtop method for sterilizing small pieces of
equipment like loops .
Question 5
The Swedish botanist known for developing an important biological classification
system is:
, A. Ernst Haeckel
B. Carolus Linnaeus
C. Louis Pasteur
D. Robert Whittaker
Answer: B
Rationale: Carolus Linnaeus, the Swedish botanist, developed the taxonomic
system for categorizing organisms into related groups, including the binomial
nomenclature system .
Question 6
Which are the three currently accepted domains?
A. Archaea, Bacteria, and Eukarya
B. Archaea, Prokaryota, and Eukaryota
C. Bacteria, Fungi, and Protista
D. Bacteria, Prokaryota, and Eukarya
Answer: A
Rationale: The three-domain system, proposed by Carl Woese and George Fox,
includes the domains Archaea, Bacteria, and Eukarya. This classification is based
on differences in rRNA genes .
Question 7
Which two taxonomic units are typically used to identify an organism when using
binomial nomenclature?
A. Domain and kingdom
B. Kingdom and phylum
C. Genus and species
D. Phylum and class
Answer: C
exam questions and answers
CHAPTER 1: AN INVISIBLE WORLD
Question 1
Which of the following is true of the microbial world?
A. All microbes are harmful.
B. Humans could survive without microbes.
C. Many microbes are helpful.
D. Most microbes are pathogenic.
Answer: C
Rationale: The vast majority of microbes are either harmless or beneficial to
humans. Only a small fraction of microorganisms are pathogenic. Microbes play
essential roles in nutrient cycling, digestion, and many industrial processes .
Question 2
When did humans first suspect the existence of microbes?
A. During the Industrial Revolution
B. In prehistoric times
C. In the last century
D. Within the last 500 years
Answer: B
Rationale: Ancient texts and practices suggest that humans suspected the
existence of invisible agents of disease and decay in prehistoric times, long before
microbes were directly observed .
,Question 3
Who first observed unicellular organisms, which he called "animalcules," using a
microscope he developed?
A. Robert Koch
B. Louis Pasteur
C. Thucydides
D. Antonie van Leeuwenhoek
Answer: D
Rationale: Antonie van Leeuwenhoek is credited with the first observation of
unicellular organisms, which he called "animalcules," using a single-lens
microscope of his own design .
Question 4
To reduce the risk of open flame from Bunsen burners, microbiologists are
increasingly using which device for easy, rapid benchtop sterilization of small
pieces of equipment?
A. Autoclaves
B. Ethylene oxide
C. Incubators
D. Microincinerators
Answer: D
Rationale: Microincinerators are increasingly used to reduce the risk of open
flames. They provide a flameless, benchtop method for sterilizing small pieces of
equipment like loops .
Question 5
The Swedish botanist known for developing an important biological classification
system is:
, A. Ernst Haeckel
B. Carolus Linnaeus
C. Louis Pasteur
D. Robert Whittaker
Answer: B
Rationale: Carolus Linnaeus, the Swedish botanist, developed the taxonomic
system for categorizing organisms into related groups, including the binomial
nomenclature system .
Question 6
Which are the three currently accepted domains?
A. Archaea, Bacteria, and Eukarya
B. Archaea, Prokaryota, and Eukaryota
C. Bacteria, Fungi, and Protista
D. Bacteria, Prokaryota, and Eukarya
Answer: A
Rationale: The three-domain system, proposed by Carl Woese and George Fox,
includes the domains Archaea, Bacteria, and Eukarya. This classification is based
on differences in rRNA genes .
Question 7
Which two taxonomic units are typically used to identify an organism when using
binomial nomenclature?
A. Domain and kingdom
B. Kingdom and phylum
C. Genus and species
D. Phylum and class
Answer: C
