OpenStax Microbiology Test Bank | Chapters
1–26 Verified Questions, Answers and
Rationales Guide
Chapter 1: An Invisible World
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.
Correct Answer: C
Rationale: The vast majority of microorganisms are either harmless or beneficial
to humans, playing essential roles in nutrient cycling, digestion, and many
industrial processes. Only a small fraction of microorganisms are pathogenic .
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
Correct 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 .
3. Which individual 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
Correct Answer: D
,Rationale: Antonie van Leeuwenhoek, using his self-crafted microscopes, was the
first to observe and describe bacteria and protozoa, which he called
"animalcules" .
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
Correct Answer: D
Rationale: Microincinerators are used for the rapid sterilization of small
equipment like inoculating loops, reducing the need for an open flame in the
laboratory .
5. The Swedish botanist known for having developed an important biological
classification system is:
A. Ernst Haeckel
B. Carolus Linnaeus
C. Louis Pasteur
D. Robert Whittaker
Correct Answer: B
Rationale: Carolus Linnaeus developed a foundational biological classification
system and is known for establishing binomial nomenclature .
6. Which kingdom was the only one found in Empire Prokaryota?
A. Animalia
B. Fungi
C. Monera
D. Protista
Correct Answer: C
Rationale: In older five-kingdom classification systems, the kingdom Monera
, comprised all prokaryotic organisms, which are now divided into the domains
Bacteria and Archaea .
7. 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
Correct Answer: A
Rationale: The three domains of life are Archaea, Bacteria, and Eukarya, based on
molecular and phylogenetic evidence .
8. Which two taxonomic units are typically used to identify an organism when
using binomial nomenclature?
A. domain and kingdom
B. genus and family
C. genus and species
D. phylum and class
Correct Answer: C
Rationale: Binomial nomenclature assigns each organism a two-part scientific
name consisting of the genus (capitalized) and the species epithet (lowercase),
both italicized or underlined .
9. Which of the following is not true about the process of fermentation?
A. It can help preserve foods, preventing spoilage.
B. It converts sugars to organic acids, alcohols, and/or gases.
C. It is carried out exclusively by unicellular eukaryotes such as yeast.
D. It is used to make foods such as cheese and bread.
Correct Answer: C
Rationale: Fermentation is not exclusive to unicellular eukaryotes; many bacteria
also perform fermentation to produce energy .
10. The Romans may have reduced their risk of waterborne infectious diseases
by using which of the following?
A. a variety of pharmaceutical products
1–26 Verified Questions, Answers and
Rationales Guide
Chapter 1: An Invisible World
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.
Correct Answer: C
Rationale: The vast majority of microorganisms are either harmless or beneficial
to humans, playing essential roles in nutrient cycling, digestion, and many
industrial processes. Only a small fraction of microorganisms are pathogenic .
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
Correct 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 .
3. Which individual 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
Correct Answer: D
,Rationale: Antonie van Leeuwenhoek, using his self-crafted microscopes, was the
first to observe and describe bacteria and protozoa, which he called
"animalcules" .
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
Correct Answer: D
Rationale: Microincinerators are used for the rapid sterilization of small
equipment like inoculating loops, reducing the need for an open flame in the
laboratory .
5. The Swedish botanist known for having developed an important biological
classification system is:
A. Ernst Haeckel
B. Carolus Linnaeus
C. Louis Pasteur
D. Robert Whittaker
Correct Answer: B
Rationale: Carolus Linnaeus developed a foundational biological classification
system and is known for establishing binomial nomenclature .
6. Which kingdom was the only one found in Empire Prokaryota?
A. Animalia
B. Fungi
C. Monera
D. Protista
Correct Answer: C
Rationale: In older five-kingdom classification systems, the kingdom Monera
, comprised all prokaryotic organisms, which are now divided into the domains
Bacteria and Archaea .
7. 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
Correct Answer: A
Rationale: The three domains of life are Archaea, Bacteria, and Eukarya, based on
molecular and phylogenetic evidence .
8. Which two taxonomic units are typically used to identify an organism when
using binomial nomenclature?
A. domain and kingdom
B. genus and family
C. genus and species
D. phylum and class
Correct Answer: C
Rationale: Binomial nomenclature assigns each organism a two-part scientific
name consisting of the genus (capitalized) and the species epithet (lowercase),
both italicized or underlined .
9. Which of the following is not true about the process of fermentation?
A. It can help preserve foods, preventing spoilage.
B. It converts sugars to organic acids, alcohols, and/or gases.
C. It is carried out exclusively by unicellular eukaryotes such as yeast.
D. It is used to make foods such as cheese and bread.
Correct Answer: C
Rationale: Fermentation is not exclusive to unicellular eukaryotes; many bacteria
also perform fermentation to produce energy .
10. The Romans may have reduced their risk of waterborne infectious diseases
by using which of the following?
A. a variety of pharmaceutical products
