TEXTBOOK OF DIAGNOSTIC
MICROBIOLOGY 7TH EDITION
PRACTICE SET 2026 CHAPTERS 1 TO
41 TESTED QUESTIONS AND
ACCURATE ANSWERS
◉ Which of the following elements is NOT correctly matched with its
cellular function? Answer: phosphorus used for production of
carbohydrates
◉ Pathogenic bacteria isolated from the respiratory or intestinal tracts of
humans are Answer: capnophiles that grow best in carbon dioxide
incubators.
◉ The biosafety level (BSL) for most introductory microbiology
laboratories is Answer: BSL-1.
◉ The biosafety level (BSL) for a clinical microbiology laboratory
working with potentially airborne pathogens, such as tuberculosis
bacteria, is Answer: BSL-3.
◉ A sample of milk is tested for its bacterial content in a plate count
assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution
series. One milliliter of the third dilution tube is plated in a pour plate.
,After incubation, the plate has 54 colonies, indicating that the original
milk sample contained Answer: 54,000 cells per milliliter.
◉ The addition of which of the following to a culture medium will
neutralize acids? Answer: buffers
◉ Salts and sugars work to preserve foods by creating a Answer:
hypertonic environment.
◉ The term aerotolerant anaerobe refers to an organism that Answer:
does not use oxygen but tolerates it.
◉ Which of the following is an advantage of the standard plate count?
Answer: determines the number of viable cells
◉ Which of the following is an advantage of the direct microscopic
count? Answer: requires no incubation time
◉ Most bacteria reproduce by Answer: binary fission.
◉ Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted
sample in a standard plate count. How many cells were in the original
sample? Answer: 36 per milliliter
◉ Most bacteria grow best at pH Answer: 7
,◉ Most fungi grow best at pH Answer: 5
◉ Consider a culture medium on which only gram-positive organisms
such as Staphylococcus aureus colonies can grow due to an elevated
NaCl level. A yellow halo surrounds the growth, indicating the
bacterium fermented a sugar in the medium, decreasing the pH as a
result and changing the color of a pH indicator chemical. This type of
medium would be referred to as a(n) Answer: selective and differential
medium.
◉ A culture medium consisting of agar, peptone, and beef heart is a
Answer: complex medium
◉ Which of the following pairs of microbe classification terms and
optimal growth temperatures is mismatched? Answer: thermophile
growth at 37C
◉ During which growth phase will gram-positive bacteria be most
susceptible to penicillin? Answer: log phase
◉ Which of the following is the best definition of generation time?
Answer: the length of time needed for a cell to divide
◉ Which of the following is NOT a direct method to measure microbial
growth? Answer: metabolic activity
, ◉ Which group of microorganisms is most likely to spoil a freshwater
trout preserved with salt? Answer: facultative halophiles
◉ Which of the following is an organic growth factor? Answer: vitamin
B1
◉ Which of the following is an example of a metabolic activity that
could be used to measure microbial growth? Answer: glucose
consumption
◉ An experiment began with 4 cells and ended with 128 cells. How
many generations did the cells go through? Answer: 5
◉ Three cells with generation times of 60 minutes are inoculated into a
culture medium. How many cells are there after 5 hours? Answer: 96
◉ In one hospital, Pseudomonas aeruginosa serotype 10 infected the
biliary tract of 10 percent of 1300 patients who underwent
gastrointestinal endoscopic procedures. After each use, endoscopes were
washed with an automatic reprocessor that flushed detergent and
glutaraldehyde through the endoscopes, followed by a tap water rinse. P.
aeruginosa serotype 10 was not isolated from the detergent,
glutaraldehyde, or tap water. What was the source of the infections?
Answer: a biofilm in the reprocessor
MICROBIOLOGY 7TH EDITION
PRACTICE SET 2026 CHAPTERS 1 TO
41 TESTED QUESTIONS AND
ACCURATE ANSWERS
◉ Which of the following elements is NOT correctly matched with its
cellular function? Answer: phosphorus used for production of
carbohydrates
◉ Pathogenic bacteria isolated from the respiratory or intestinal tracts of
humans are Answer: capnophiles that grow best in carbon dioxide
incubators.
◉ The biosafety level (BSL) for most introductory microbiology
laboratories is Answer: BSL-1.
◉ The biosafety level (BSL) for a clinical microbiology laboratory
working with potentially airborne pathogens, such as tuberculosis
bacteria, is Answer: BSL-3.
◉ A sample of milk is tested for its bacterial content in a plate count
assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution
series. One milliliter of the third dilution tube is plated in a pour plate.
,After incubation, the plate has 54 colonies, indicating that the original
milk sample contained Answer: 54,000 cells per milliliter.
◉ The addition of which of the following to a culture medium will
neutralize acids? Answer: buffers
◉ Salts and sugars work to preserve foods by creating a Answer:
hypertonic environment.
◉ The term aerotolerant anaerobe refers to an organism that Answer:
does not use oxygen but tolerates it.
◉ Which of the following is an advantage of the standard plate count?
Answer: determines the number of viable cells
◉ Which of the following is an advantage of the direct microscopic
count? Answer: requires no incubation time
◉ Most bacteria reproduce by Answer: binary fission.
◉ Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted
sample in a standard plate count. How many cells were in the original
sample? Answer: 36 per milliliter
◉ Most bacteria grow best at pH Answer: 7
,◉ Most fungi grow best at pH Answer: 5
◉ Consider a culture medium on which only gram-positive organisms
such as Staphylococcus aureus colonies can grow due to an elevated
NaCl level. A yellow halo surrounds the growth, indicating the
bacterium fermented a sugar in the medium, decreasing the pH as a
result and changing the color of a pH indicator chemical. This type of
medium would be referred to as a(n) Answer: selective and differential
medium.
◉ A culture medium consisting of agar, peptone, and beef heart is a
Answer: complex medium
◉ Which of the following pairs of microbe classification terms and
optimal growth temperatures is mismatched? Answer: thermophile
growth at 37C
◉ During which growth phase will gram-positive bacteria be most
susceptible to penicillin? Answer: log phase
◉ Which of the following is the best definition of generation time?
Answer: the length of time needed for a cell to divide
◉ Which of the following is NOT a direct method to measure microbial
growth? Answer: metabolic activity
, ◉ Which group of microorganisms is most likely to spoil a freshwater
trout preserved with salt? Answer: facultative halophiles
◉ Which of the following is an organic growth factor? Answer: vitamin
B1
◉ Which of the following is an example of a metabolic activity that
could be used to measure microbial growth? Answer: glucose
consumption
◉ An experiment began with 4 cells and ended with 128 cells. How
many generations did the cells go through? Answer: 5
◉ Three cells with generation times of 60 minutes are inoculated into a
culture medium. How many cells are there after 5 hours? Answer: 96
◉ In one hospital, Pseudomonas aeruginosa serotype 10 infected the
biliary tract of 10 percent of 1300 patients who underwent
gastrointestinal endoscopic procedures. After each use, endoscopes were
washed with an automatic reprocessor that flushed detergent and
glutaraldehyde through the endoscopes, followed by a tap water rinse. P.
aeruginosa serotype 10 was not isolated from the detergent,
glutaraldehyde, or tap water. What was the source of the infections?
Answer: a biofilm in the reprocessor
