MICROBIOLOGY UNIT 2 EXAM QUESTIONS
WITH CORRECT ANSWERS 2025/2026
Biochemical tests are used to determine - CORRECT ANSWER -enzymatic activities.
You have isolated a prokaryotic cell. The first step in identification is a(n) - CORRECT ANSWER -
Gram stain.
Which of the following criteria is most useful in determining whether two organisms are
related?
A. Both are aerobic.
B. Both are gram-positive.
C. Both are motile.
D. Both ferment lactose.
E. Each answer is equally important. - CORRECT ANSWER -B. Both are gram-positive.
Staphylococcus and Streptococcus can be easily differentiated in a laboratory by which one of
the following?
A. Gram stain reaction
B. glucose fermentation
C. growth in high salt concentrations
D. cell shape
E. ability to cause disease - CORRECT ANSWER -C. growth in high salt concentrations
Streptomyces differs from Actinomyces because Streptomyces
A. is a strict aerobe.
B. forms filaments.
,C. produces conidia.
D. makes antibiotics.
E. is a bacterium. - CORRECT ANSWER -A. is a strict aerobe.
Which of the following pairs is NOT correctly matched?
A. elementary body - Escherichia
B. endospore - Clostridium
C. endospore - Bacillus
D. heterocyst - cyanobacteria
E. myxospore - gliding bacteria - CORRECT ANSWER -A. elementary body - Escherichia
Which of the following statements is a reason for NOT classifying viruses in one of three
domains rather than in a fourth domain?
A. Some viruses can incorporate their genome into a host's genome.
B. Viruses direct anabolic pathways of host cells.
C. Viruses are not composed of cells.
D. Viruses are obligate parasites.
E. All of the answers are correct. - CORRECT ANSWER -C. Viruses are not composed of cells.
Which of the following bacteria is gram-negative?
A. Staphylococcus
B. Mycobacterium
C. Treponema
D. Bacillus
E. Corynebacterium - CORRECT ANSWER -C. Treponema
,Both Beggiatoa and the purple sulfur bacteria use H2S. These bacteria differ in that Beggiatoa
A. belongs to the gammaproteobacteria.
B. uses light energy.
C. is a heterotroph.
D. uses H2S for an energy source.
E. uses H2S for a carbon source. - CORRECT ANSWER -D. uses H2S for an energy source.
You have isolated a bacterium that grows in a medium containing an organic substrate and
nitrate in the absence of oxygen. The nitrate is reduced to nitrogen gas. You can be sure that
this bacterium is
A. gram-positive.
B. using anaerobic respiration.
C. a photoautotroph.
D. a chemoautotroph.
E. a photoheterotroph. - CORRECT ANSWER -B. using anaerobic respiration.
Which of the following form conidiospores?
A. endospore-forming gram-positive rods and cocci
B. rickettsias
C. anaerobic gram-negative cocci
D. spiral and curved bacteria
E. actinomycetes and related organisms - CORRECT ANSWER -E. actinomycetes and related
organisms
Which of the following is NOT a characteristic of Neisseria?
A. gram-negative
B. cocci
, C. requires X and V factors
D. oxidase-positive
E. Some species are human pathogens. - CORRECT ANSWER -C. requires X and V factors
In the scientific name Enterobacter aerogenes, Enterobacter is the - CORRECT ANSWER -genus
Fossil evidence indicates that prokaryotic cells first existed on the Earth _____ years ago. -
CORRECT ANSWER -3.5 billion
Which of the following statements about members of the Kingdom Plantae is false?
A. They undergo photosynthesis.
B. They use organic carbon sources.
C. They synthesize organic molecules.
D. They are composed of eukaryotic cells.
E. They are multicellular. - CORRECT ANSWER -B. They use organic carbon sources.
Which of the following is most likely a product of an early gene?
A. spike proteins
B. lysozyme
C. DNA polymerase
D. envelope proteins
E. capsid proteins - CORRECT ANSWER -C. DNA polymerase
Which of the following is necessary for replication of a prion? - CORRECT ANSWER -PrPSc
Which of the following statements regarding fungi is FALSE?
WITH CORRECT ANSWERS 2025/2026
Biochemical tests are used to determine - CORRECT ANSWER -enzymatic activities.
You have isolated a prokaryotic cell. The first step in identification is a(n) - CORRECT ANSWER -
Gram stain.
Which of the following criteria is most useful in determining whether two organisms are
related?
A. Both are aerobic.
B. Both are gram-positive.
C. Both are motile.
D. Both ferment lactose.
E. Each answer is equally important. - CORRECT ANSWER -B. Both are gram-positive.
Staphylococcus and Streptococcus can be easily differentiated in a laboratory by which one of
the following?
A. Gram stain reaction
B. glucose fermentation
C. growth in high salt concentrations
D. cell shape
E. ability to cause disease - CORRECT ANSWER -C. growth in high salt concentrations
Streptomyces differs from Actinomyces because Streptomyces
A. is a strict aerobe.
B. forms filaments.
,C. produces conidia.
D. makes antibiotics.
E. is a bacterium. - CORRECT ANSWER -A. is a strict aerobe.
Which of the following pairs is NOT correctly matched?
A. elementary body - Escherichia
B. endospore - Clostridium
C. endospore - Bacillus
D. heterocyst - cyanobacteria
E. myxospore - gliding bacteria - CORRECT ANSWER -A. elementary body - Escherichia
Which of the following statements is a reason for NOT classifying viruses in one of three
domains rather than in a fourth domain?
A. Some viruses can incorporate their genome into a host's genome.
B. Viruses direct anabolic pathways of host cells.
C. Viruses are not composed of cells.
D. Viruses are obligate parasites.
E. All of the answers are correct. - CORRECT ANSWER -C. Viruses are not composed of cells.
Which of the following bacteria is gram-negative?
A. Staphylococcus
B. Mycobacterium
C. Treponema
D. Bacillus
E. Corynebacterium - CORRECT ANSWER -C. Treponema
,Both Beggiatoa and the purple sulfur bacteria use H2S. These bacteria differ in that Beggiatoa
A. belongs to the gammaproteobacteria.
B. uses light energy.
C. is a heterotroph.
D. uses H2S for an energy source.
E. uses H2S for a carbon source. - CORRECT ANSWER -D. uses H2S for an energy source.
You have isolated a bacterium that grows in a medium containing an organic substrate and
nitrate in the absence of oxygen. The nitrate is reduced to nitrogen gas. You can be sure that
this bacterium is
A. gram-positive.
B. using anaerobic respiration.
C. a photoautotroph.
D. a chemoautotroph.
E. a photoheterotroph. - CORRECT ANSWER -B. using anaerobic respiration.
Which of the following form conidiospores?
A. endospore-forming gram-positive rods and cocci
B. rickettsias
C. anaerobic gram-negative cocci
D. spiral and curved bacteria
E. actinomycetes and related organisms - CORRECT ANSWER -E. actinomycetes and related
organisms
Which of the following is NOT a characteristic of Neisseria?
A. gram-negative
B. cocci
, C. requires X and V factors
D. oxidase-positive
E. Some species are human pathogens. - CORRECT ANSWER -C. requires X and V factors
In the scientific name Enterobacter aerogenes, Enterobacter is the - CORRECT ANSWER -genus
Fossil evidence indicates that prokaryotic cells first existed on the Earth _____ years ago. -
CORRECT ANSWER -3.5 billion
Which of the following statements about members of the Kingdom Plantae is false?
A. They undergo photosynthesis.
B. They use organic carbon sources.
C. They synthesize organic molecules.
D. They are composed of eukaryotic cells.
E. They are multicellular. - CORRECT ANSWER -B. They use organic carbon sources.
Which of the following is most likely a product of an early gene?
A. spike proteins
B. lysozyme
C. DNA polymerase
D. envelope proteins
E. capsid proteins - CORRECT ANSWER -C. DNA polymerase
Which of the following is necessary for replication of a prion? - CORRECT ANSWER -PrPSc
Which of the following statements regarding fungi is FALSE?
