OSX Microbiology Test Bank Chapter 4 Exam Questions Practice Test Bank 2025/ 2026

OpenStax Microbiology Test Bank
Chapter 4: Prokaryotic Diversity

Chapter 4: Prokaryotic Diversity

* = Correct answer

Multiple Choice

1. Which is the best example of a population?
A. all the microbes living in a particular area
B. all the microbes of a particular domain living in a particular area
C. all the microbes of a single species living in a particular area*
D. all the microbes living within the same host

Difficulty: Moderate
ASM Standard: 20

2. Microbial ecology is defined as the study of which of the following?
A. competitive interactions between microbes
B. cooperative interactions between microbes
C. interactions between individuals of a single species
D. interactions between microbial populations and their environment*

Difficulty: Easy
ASM Standard: 20

3. Which term best describes the relationship between pathogenic bacteria and humans?
A. amensalism
B. commensalism
C. parasitism*
D. predation

Difficulty: Moderate
ASM Standard: 23

4. Which of the following is not a class within the phylum Proteobacteria?
A. Alphaproteobacteria
B. Betaproteobacteria
C. Deltaproteobacteria
D. Omegaproteobacteria*

Difficulty: Easy
ASM Standard: N/A

5. Which of the following correctly characterizes Epsilonproteobacteria?
A. They are atypical (not gram positive or gram negative).
B. They are gram negative.*
C. They are gram positive.


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,OpenStax Microbiology Test Bank
Chapter 4: Prokaryotic Diversity

D. They are gram variable.

Difficulty: Easy
ASM Standard: 34

6. Which describes bacteria that require low concentrations of oxygen to survive (less than that
in the current atmosphere)?
A. facultative anaerobes
B. microaerophiles*
C. obligate aerobes
D. obligate anaerobes

Difficulty: Easy
ASM Standard: 11, 22

7. Cyanobacteria produce which of the following?
A. hydrogen sulfide gas
B. large quantities of ammonia
C. oxygen*
D. sulfuric acid

Difficulty: Easy
ASM Standard: 11, 22

8. Which of the following bacterial groups is thought to be most closely related to the last
universal common ancestor?
A. Alphaproteobacteria
B. cyanobacteria
C. deeply branching bacteria*
D. green filamentous bacteria

Difficulty: Easy
ASM Standard: 5

9. Which of the following is a phylum in Domain Archaea?
A. Crenarchaeotae*
B. Deinococcus
C. Mycoplasma
D. Thermotogae

Difficulty: Easy
ASM Standard: 5

10. Which genus contains the nitrogen-fixing bacteria that live in legume nodules?
A. Bacillus
B. Escherichia


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, OpenStax Microbiology Test Bank
Chapter 4: Prokaryotic Diversity

C. Rhizobium*
D. Vibrio

Difficulty: Moderate
ASM Standard: 11, 24

11. Approximately what percentage of prokaryotes are thought to be pathogens?
A. <1%*
B. 12%
C. 26%
D. 48%

Difficulty: Moderate
ASM Standard: 23

12. Two species of bacteria live in near each other and use similar food resources. Which type of
biological interaction does this describe?
A. a competitive interaction*
B. a cooperative interaction
C. a mutualistic interaction
D. a parasitic interaction

Difficulty: Moderate
ASM Standard: 23

13. Which of the following is a source of vitamin K for humans?
A. Bacteroides thetaiotetraiotamicron digests foods, which release vitamin K.
B. Escherichia coli in their digestive tract produces vitamin K.*
C. S. epidermidis releases vitamin K from dead cells.
D. their diet only

Difficulty: Moderate
ASM Standard: 23, 24

14. The human microbiome consists of which of the following?
A. all microbes present on or in the body*
B. pathogenic microbes only
C. resident microbes only
D. transient microbes only

Difficulty: Moderate
ASM Standard: 23

15. The most common bacterial genus found in plaque on teeth is which of the following?
A. Fusobacterium*
B. Haemophilus


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