ANSWER KEY FOR OpenStax Microbiology Test Bank /
OSX Microbiology
Test Bank - Chapter 01 to Chapter 26 2025 Update
Correct answer
Multiple Choice
1. Which of the following is when humans first suspected the existence of microbes?
A. during the Industrial Revolution
B. in prehistoric * (correct times
C. in the last century answer)
D. within the last 500 years
Difficulty: Easy
ASM Standard: 23
2. 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 * (correct Leeuwenhoek
answer)
Difficulty: Easy
ASM Standard: 6
3. To reduce the risk of open flame from Bunsen burners, microbiologists are increasingly using
which of the following devices for easy, rapid benchtop sterilization of small pieces of
equipment? A. autoclaves
B. ethylene oxide
C. incubators
* (correct D. microincinerators
answer)
Difficulty: Easy
ASM Standard: 36
4. 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 * (correct helpful.
D. Most microbes are answer) pathogenic.
Difficulty: Easy
,OpenStaxMicrobiologyTestBank Chapter
1: An Invisible World
ASM Standard: 23, 24
5. Which kingdom was the only one found in Empire Prokaryota?
A. Animalia
B. Fungi
* (correct C. Monera D. Protista
answer)
Difficulty: Easy
ASM Standard: N/A
6. The Swedish botanist known for having developed an important biological classification system
is which of the following people?
A. Ernst Haeckel
B. Carolus * (correct Linnaeus
C. Louis Pasteur answer)
D. Robert Whittaker
Difficulty: Easy
ASM Standard: N/A
7. Which are the three currently accepted domains?
A. Archaea, Bacteria, and * (correct Eukarya
B. Archaea, Prokaryota, and answer) Eukaryota
C. Bacteria, Fungi, and Protista
D. Bacteria, Prokaryota, and Eukarya
Difficulty: Easy
ASM Standard: N/A
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 * (correct species
D. phylum and answer) class
Difficulty: Easy
ASM Standard: N/A
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 such as carbon dioxide.
Page 1 of 17
,OpenStaxMicrobiologyTestBank Chapter
1: An Invisible World
C. It is carried out exclusively by unicellular eukaryotes such as * (correct yeast.
D. It is used to make foods such as cheese and bread. answer)
Difficulty: Moderate
ASM Standard: 11, 23, 26
10. For which of the following is Thucydides known?
A. developing an effective sewer system in ancient Greece, helping to reduce levels of disease in
cities
B. observing microbes, using a microscope, for the first time, even distinguishing between
bacteria and fungi
C. proposing that disease was caused by microorganisms
D. realizing that people who had been infected by the Athenian plague had immunity to
reinfection* (correct answer)
Difficulty: Moderate
ASM Standard: 23, 31
11. The Romans may have reduced their risk of waterborne infectious diseases by using which of
the following?
A. a variety of pharmaceutical products
B. aqueducts and a sewer * (correct system
C. prophylactic antibiotics answer)
D. quarantine of people with leprosy
Difficulty: Moderate
ASM Standard: 23
12. Ernst Haeckel proposed a classification system consisting of which of the following subgroups?
A. five kingdoms
B. four * (correct kingdoms
C. two domains answer) and three kingdoms
D. two domains and five kingdoms
Difficulty: Moderate
ASM Standard: N/A
13. Viruses not included in phylogenetic trees for which of the following reasons? A. It is too
difficult to observe their characteristics.
B. They are acellular and * (correct nonliving.
C. They do not have any genes, answer) which prevents genetic analysis.
D. They lack a nucleus.
Difficulty: Moderate
ASM Standard: 5
Page 2 of 17
, OpenStaxMicrobiologyTestBank Chapter
1: An Invisible World
14. Which is the best description of the primary purpose of a phylogeny? A. Phylogenies show all
the alterative names for each species.
B. Phylogenies show all the common names for each species.
C. Phylogenies show evolutionary relatedness between * (correct organisms.
D. Phylogenies show interactions between species in a shared answer) habitat.
Difficulty: Moderate
ASM Standard: 5
15. Current phylogenetic analyses include which of the following?
A. information from a range of sources, including morphological, genetic, and biochemical
data* (correct answer)
B. information on visible similarities only
C. information regarding how to classify organisms on the basis of external morphological
characteristics and visible behaviors
D. varied morphological and structural characteristics, with preference for leaving historical
classifications to prevent confusion
Difficulty: Moderate
ASM Standard: 5
16. Diatoms are classified within which of the following domains?
A. Archaea
B. Bacteria
* (correct C. Eukarya
answer) D. Prokaryota
Difficulty: Moderate
ASM Standard: N/A
17. Horizontal gene transfer involves which of the following?
A. any transfer of genes in a laboratory setting
B. the transfer of genes from a virus to a bacterium or vice versa but not any other form of gene
transfer
C. the transfer of genes from one individual to another, including from
one species to another, but not from * (correct answer) parent to offspring D. the transfer of
genes from parent to offspring
Difficulty: Moderate
ASM Standard: 2, 4
18. Bacteria are generally identified to species by using which of the following?
A. a combination of genetic, biochemical, and microscopic * (correct
approaches answer)
B. a combination of microscopic and physiological approaches, but not
genetics
Page 3 of 17
OSX Microbiology
Test Bank - Chapter 01 to Chapter 26 2025 Update
Correct answer
Multiple Choice
1. Which of the following is when humans first suspected the existence of microbes?
A. during the Industrial Revolution
B. in prehistoric * (correct times
C. in the last century answer)
D. within the last 500 years
Difficulty: Easy
ASM Standard: 23
2. 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 * (correct Leeuwenhoek
answer)
Difficulty: Easy
ASM Standard: 6
3. To reduce the risk of open flame from Bunsen burners, microbiologists are increasingly using
which of the following devices for easy, rapid benchtop sterilization of small pieces of
equipment? A. autoclaves
B. ethylene oxide
C. incubators
* (correct D. microincinerators
answer)
Difficulty: Easy
ASM Standard: 36
4. 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 * (correct helpful.
D. Most microbes are answer) pathogenic.
Difficulty: Easy
,OpenStaxMicrobiologyTestBank Chapter
1: An Invisible World
ASM Standard: 23, 24
5. Which kingdom was the only one found in Empire Prokaryota?
A. Animalia
B. Fungi
* (correct C. Monera D. Protista
answer)
Difficulty: Easy
ASM Standard: N/A
6. The Swedish botanist known for having developed an important biological classification system
is which of the following people?
A. Ernst Haeckel
B. Carolus * (correct Linnaeus
C. Louis Pasteur answer)
D. Robert Whittaker
Difficulty: Easy
ASM Standard: N/A
7. Which are the three currently accepted domains?
A. Archaea, Bacteria, and * (correct Eukarya
B. Archaea, Prokaryota, and answer) Eukaryota
C. Bacteria, Fungi, and Protista
D. Bacteria, Prokaryota, and Eukarya
Difficulty: Easy
ASM Standard: N/A
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 * (correct species
D. phylum and answer) class
Difficulty: Easy
ASM Standard: N/A
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 such as carbon dioxide.
Page 1 of 17
,OpenStaxMicrobiologyTestBank Chapter
1: An Invisible World
C. It is carried out exclusively by unicellular eukaryotes such as * (correct yeast.
D. It is used to make foods such as cheese and bread. answer)
Difficulty: Moderate
ASM Standard: 11, 23, 26
10. For which of the following is Thucydides known?
A. developing an effective sewer system in ancient Greece, helping to reduce levels of disease in
cities
B. observing microbes, using a microscope, for the first time, even distinguishing between
bacteria and fungi
C. proposing that disease was caused by microorganisms
D. realizing that people who had been infected by the Athenian plague had immunity to
reinfection* (correct answer)
Difficulty: Moderate
ASM Standard: 23, 31
11. The Romans may have reduced their risk of waterborne infectious diseases by using which of
the following?
A. a variety of pharmaceutical products
B. aqueducts and a sewer * (correct system
C. prophylactic antibiotics answer)
D. quarantine of people with leprosy
Difficulty: Moderate
ASM Standard: 23
12. Ernst Haeckel proposed a classification system consisting of which of the following subgroups?
A. five kingdoms
B. four * (correct kingdoms
C. two domains answer) and three kingdoms
D. two domains and five kingdoms
Difficulty: Moderate
ASM Standard: N/A
13. Viruses not included in phylogenetic trees for which of the following reasons? A. It is too
difficult to observe their characteristics.
B. They are acellular and * (correct nonliving.
C. They do not have any genes, answer) which prevents genetic analysis.
D. They lack a nucleus.
Difficulty: Moderate
ASM Standard: 5
Page 2 of 17
, OpenStaxMicrobiologyTestBank Chapter
1: An Invisible World
14. Which is the best description of the primary purpose of a phylogeny? A. Phylogenies show all
the alterative names for each species.
B. Phylogenies show all the common names for each species.
C. Phylogenies show evolutionary relatedness between * (correct organisms.
D. Phylogenies show interactions between species in a shared answer) habitat.
Difficulty: Moderate
ASM Standard: 5
15. Current phylogenetic analyses include which of the following?
A. information from a range of sources, including morphological, genetic, and biochemical
data* (correct answer)
B. information on visible similarities only
C. information regarding how to classify organisms on the basis of external morphological
characteristics and visible behaviors
D. varied morphological and structural characteristics, with preference for leaving historical
classifications to prevent confusion
Difficulty: Moderate
ASM Standard: 5
16. Diatoms are classified within which of the following domains?
A. Archaea
B. Bacteria
* (correct C. Eukarya
answer) D. Prokaryota
Difficulty: Moderate
ASM Standard: N/A
17. Horizontal gene transfer involves which of the following?
A. any transfer of genes in a laboratory setting
B. the transfer of genes from a virus to a bacterium or vice versa but not any other form of gene
transfer
C. the transfer of genes from one individual to another, including from
one species to another, but not from * (correct answer) parent to offspring D. the transfer of
genes from parent to offspring
Difficulty: Moderate
ASM Standard: 2, 4
18. Bacteria are generally identified to species by using which of the following?
A. a combination of genetic, biochemical, and microscopic * (correct
approaches answer)
B. a combination of microscopic and physiological approaches, but not
genetics
Page 3 of 17
