Microbiology (Tortora 12th edition)
Chapter 6, 7, 10, 11, 12 test bank
LATEST UPDATES!!! 2026-2027 |
CORRECT SOLUTIONS WITH QUIZ &
ANSWERS | HIGHLY GRADED A+
If cells are grown in media containing amino acids labeled with radioactive nitrogen
(15N), most of the radioactivity will be found in the cells - CORRECT ANSWERS-DNA
and proteins.
Which of the following elements is NOT correctly matched with its cellular function? -
CORRECT ANSWERS-phosphorus used for production of carbohydrates
Pathogenic bacteria isolated from the respiratory or intestinal tracts of humans are -
CORRECT ANSWERS-capnophiles that grow best in carbon dioxide incubators.
The biosafety level (BSL) for most introductory microbiology laboratories is - CORRECT
ANSWERS-BSL-1.
The biosafety level (BSL) for a clinical microbiology laboratory working with potentially
airborne pathogens, such as tuberculosis bacteria, is - CORRECT ANSWERS-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 - CORRECT ANSWERS-54,000 cells per milliliter.
The addition of which of the following to a culture medium will neutralize acids? -
CORRECT ANSWERS-buffers
Salts and sugars work to preserve foods by creating a - CORRECT ANSWERS-
hypertonic environment.
The term aerotolerant anaerobe refers to an organism that - CORRECT ANSWERS-
does not use oxygen but tolerates it.
,Which of the following is an advantage of the standard plate count? - CORRECT
ANSWERS-determines the number of viable cells
Which of the following is an advantage of the direct microscopic count? - CORRECT
ANSWERS-requires no incubation time
Most bacteria reproduce by - CORRECT ANSWERS-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? - CORRECT ANSWERS-36
per milliliter
Most bacteria grow best at pH - CORRECT ANSWERS-7
Most fungi grow best at pH - CORRECT ANSWERS-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) - CORRECT ANSWERS-selective and
differential medium.
A culture medium consisting of agar, peptone, and beef heart is a - CORRECT
ANSWERS-complex medium
Which of the following pairs of microbe classification terms and optimal growth
temperatures is mismatched? - CORRECT ANSWERS-thermophile growth at 37C
During which growth phase will gram-positive bacteria be most susceptible to penicillin?
- CORRECT ANSWERS-log phase
Which of the following is the best definition of generation time? - CORRECT
ANSWERS-the length of time needed for a cell to divide
Which of the following is NOT a direct method to measure microbial growth? -
CORRECT ANSWERS-metabolic activity
Which group of microorganisms is most likely to spoil a freshwater trout preserved with
salt? - CORRECT ANSWERS-facultative halophiles
Which of the following is an organic growth factor? - CORRECT ANSWERS-vitamin B1
Which of the following is an example of a metabolic activity that could be used to
measure microbial growth? - CORRECT ANSWERS-glucose consumption
, An experiment began with 4 cells and ended with 128 cells. How many generations did
the cells go through? - CORRECT ANSWERS-5
Three cells with generation times of 60 minutes are inoculated into a culture medium.
How many cells are there after 5 hours? - CORRECT ANSWERS-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? - CORRECT ANSWERS-a biofilm in the
reprocessor
Assume you inoculated 100 cells, with a generation time of 20 minutes, into 100 ml of
nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient
broth. After incubation for 4 hours, you can reasonably expect to have - CORRECT
ANSWERS-the same number of cells in both.
The source of nutrients in nutrient agar is - CORRECT ANSWERS-peptone and beef
extract.
Which enzyme catalyzes the reaction: O2 + O2 + 2H+ H2O2 + O2? - CORRECT
ANSWERS-superoxide dismutase
Which enzyme catalyzes the reaction: 2H2O2 2H2O + O2? - CORRECT ANSWERS-
catalase
Which enzyme catalyzes the reaction: H2O2 + 2H+ 2H2O? - CORRECT ANSWERS-
peroxidase
Patients with indwelling catheters (long-term tubes inserted into body orifices for
drainage, such as through the urethra and into the urinary bladder) are susceptible to
infections because - CORRECT ANSWERS-biofilms develop on catheters.
An isolated colony on a streak plate contains millions (or even billions) of identical cells
all arising from one initial cell. - CORRECT ANSWERS-TRUE
Bacterial growth refers to an increase in the numbers of cells in a bacterial culture. -
CORRECT ANSWERS-TRUE
Pure cultures can easily be obtained on streak plates, even if the desired bacteria are
present in very low concentrations in the initial culture broth. - CORRECT ANSWERS-
FALSE
Chapter 6, 7, 10, 11, 12 test bank
LATEST UPDATES!!! 2026-2027 |
CORRECT SOLUTIONS WITH QUIZ &
ANSWERS | HIGHLY GRADED A+
If cells are grown in media containing amino acids labeled with radioactive nitrogen
(15N), most of the radioactivity will be found in the cells - CORRECT ANSWERS-DNA
and proteins.
Which of the following elements is NOT correctly matched with its cellular function? -
CORRECT ANSWERS-phosphorus used for production of carbohydrates
Pathogenic bacteria isolated from the respiratory or intestinal tracts of humans are -
CORRECT ANSWERS-capnophiles that grow best in carbon dioxide incubators.
The biosafety level (BSL) for most introductory microbiology laboratories is - CORRECT
ANSWERS-BSL-1.
The biosafety level (BSL) for a clinical microbiology laboratory working with potentially
airborne pathogens, such as tuberculosis bacteria, is - CORRECT ANSWERS-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 - CORRECT ANSWERS-54,000 cells per milliliter.
The addition of which of the following to a culture medium will neutralize acids? -
CORRECT ANSWERS-buffers
Salts and sugars work to preserve foods by creating a - CORRECT ANSWERS-
hypertonic environment.
The term aerotolerant anaerobe refers to an organism that - CORRECT ANSWERS-
does not use oxygen but tolerates it.
,Which of the following is an advantage of the standard plate count? - CORRECT
ANSWERS-determines the number of viable cells
Which of the following is an advantage of the direct microscopic count? - CORRECT
ANSWERS-requires no incubation time
Most bacteria reproduce by - CORRECT ANSWERS-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? - CORRECT ANSWERS-36
per milliliter
Most bacteria grow best at pH - CORRECT ANSWERS-7
Most fungi grow best at pH - CORRECT ANSWERS-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) - CORRECT ANSWERS-selective and
differential medium.
A culture medium consisting of agar, peptone, and beef heart is a - CORRECT
ANSWERS-complex medium
Which of the following pairs of microbe classification terms and optimal growth
temperatures is mismatched? - CORRECT ANSWERS-thermophile growth at 37C
During which growth phase will gram-positive bacteria be most susceptible to penicillin?
- CORRECT ANSWERS-log phase
Which of the following is the best definition of generation time? - CORRECT
ANSWERS-the length of time needed for a cell to divide
Which of the following is NOT a direct method to measure microbial growth? -
CORRECT ANSWERS-metabolic activity
Which group of microorganisms is most likely to spoil a freshwater trout preserved with
salt? - CORRECT ANSWERS-facultative halophiles
Which of the following is an organic growth factor? - CORRECT ANSWERS-vitamin B1
Which of the following is an example of a metabolic activity that could be used to
measure microbial growth? - CORRECT ANSWERS-glucose consumption
, An experiment began with 4 cells and ended with 128 cells. How many generations did
the cells go through? - CORRECT ANSWERS-5
Three cells with generation times of 60 minutes are inoculated into a culture medium.
How many cells are there after 5 hours? - CORRECT ANSWERS-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? - CORRECT ANSWERS-a biofilm in the
reprocessor
Assume you inoculated 100 cells, with a generation time of 20 minutes, into 100 ml of
nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient
broth. After incubation for 4 hours, you can reasonably expect to have - CORRECT
ANSWERS-the same number of cells in both.
The source of nutrients in nutrient agar is - CORRECT ANSWERS-peptone and beef
extract.
Which enzyme catalyzes the reaction: O2 + O2 + 2H+ H2O2 + O2? - CORRECT
ANSWERS-superoxide dismutase
Which enzyme catalyzes the reaction: 2H2O2 2H2O + O2? - CORRECT ANSWERS-
catalase
Which enzyme catalyzes the reaction: H2O2 + 2H+ 2H2O? - CORRECT ANSWERS-
peroxidase
Patients with indwelling catheters (long-term tubes inserted into body orifices for
drainage, such as through the urethra and into the urinary bladder) are susceptible to
infections because - CORRECT ANSWERS-biofilms develop on catheters.
An isolated colony on a streak plate contains millions (or even billions) of identical cells
all arising from one initial cell. - CORRECT ANSWERS-TRUE
Bacterial growth refers to an increase in the numbers of cells in a bacterial culture. -
CORRECT ANSWERS-TRUE
Pure cultures can easily be obtained on streak plates, even if the desired bacteria are
present in very low concentrations in the initial culture broth. - CORRECT ANSWERS-
FALSE
