Question 1

Which of the following is NOT a direct method to measure microbial growth?

Accepted Answer

A)  most probable number (MPN) 
B)  standard plate count 
C)  direct microscopic count 
D)  metabolic activity 
E)  filtration on a support membrane followed by incubation on medium 
A)  most probable number (MPN) 
B)  standard plate count 
C)  direct microscopic count 
D)  metabolic activity 
E)  filtration on a support membrane followed by incubation on medium

Question 2

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

Accepted Answer

A)  54,000 cells per milliliter. 
B)  540,000 cells per milliliter. 
C)  5,400 cells per milliliter. 
D)  540 cells per milliliter. 
E)  54 cells per milliliter. 
A)  54,000 cells per milliliter. 
B)  540,000 cells per milliliter. 
C)  5,400 cells per milliliter. 
D)  540 cells per milliliter. 
E)  54 cells per milliliter.

Question 3

During which growth phase will gram-positive bacteria be most susceptible to penicillin?

Accepted Answer

A)  stationary phase 
B)  log phase 
C)  lag phase 
D)  death phase 
E)  The culture is equally susceptible during all phases. 
A)  stationary phase 
B)  log phase 
C)  lag phase 
D)  death phase 
E)  The culture is equally susceptible during all phases.

Question 4

Filtration methods, followed by growth of the bacteria trapped on the filters in growth media, are used to count bacteria present in very low concentrations, such as in lakes and streams.

Accepted Answer

A) True 
 B)False

Question 5

Which of the following is an advantage of the standard plate count?

Accepted Answer

A)  can readily count cells that form aggregates 
B)  provides immediate results 
C)  can be performed on very dilute samples, such as lake water 
D)  determines the number of viable cells 
E)  can be used to count heat-sensitive bacteria 
A)  can readily count cells that form aggregates 
B)  provides immediate results 
C)  can be performed on very dilute samples, such as lake water 
D)  determines the number of viable cells 
E)  can be used to count heat-sensitive bacteria

Question 6

The biosafety level (BSL) for most introductory microbiology laboratories is

Accepted Answer

A)  BSL-1. 
B)  BSL-2. 
C)  BSL-3. 
D)  BSL-4. 
A)  BSL-1. 
B)  BSL-2. 
C)  BSL-3. 
D)  BSL-4.

Question 7

The addition of which of the following to a culture medium will neutralize acids?

Accepted Answer

A)  pH 
B)  carbon 
C)  sugars 
D)  heat 
E)  buffers 
A)  pH 
B)  carbon 
C)  sugars 
D)  heat 
E)  buffers

Question 8

Most pathogenic bacteria are thermophiles.

Accepted Answer

A) True 
 B)False

Question 9

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?

Accepted Answer

A)  fecal contamination of the bile ducts 
B)  a biofilm in the reprocessor 
C)  bacterial cell walls in the water 
D)  contaminated disinfectant 
E)  None of the answers is correct. 
A)  fecal contamination of the bile ducts 
B)  a biofilm in the reprocessor 
C)  bacterial cell walls in the water 
D)  contaminated disinfectant 
E)  None of the answers is correct.

Question 10

Which of the following is the best definition of generation time?

Accepted Answer

A)  the duration of log phase 
B)  the time needed for nuclear division 
C)  the length of time needed for a cell to divide 
D)  the length of time needed for lag phase 
E)  the minimum rate of doubling 
A)  the duration of log phase 
B)  the time needed for nuclear division 
C)  the length of time needed for a cell to divide 
D)  the length of time needed for lag phase 
E)  the minimum rate of doubling

Question 11

Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases.

Accepted Answer

A) True 
 B)False

Question 12

The source of nutrients in nutrient agar is

Accepted Answer

A)  peptone and beef extract. 
B)  peptone and NaCl. 
C)  agar. 
D)  agar and NaCl. 
E)  gelatin. 
A)  peptone and beef extract. 
B)  peptone and NaCl. 
C)  agar. 
D)  agar and NaCl. 
E)  gelatin.

Question 13

Table 6.1
Three different culture media are shown below. $\begin{array}{|l|l|l|}
\hline \text { Medium A } & \text { Medium B } & \text { Medium C } \
\hline \text { Na2H PO4 } & \text { Tide detergent } & \text { Glucose } \
\hline \text { KH2PO4 } & \text { Na2HPO4 } & \text { Peptone } \\hline \mathrm{MgSO}_{4} & \mathrm{KH}_{2} \mathrm{PO}_{4} & \left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} \
\hline \mathrm{CaCl}_{2} & \mathrm{MgSO}_{4} & \mathrm{KH}_{2} \mathrm{PO}_{2} \
\hline \mathrm{NaHCO}_{3} & \left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} & \mathrm{Na}_{2} \mathrm{HPO}_{4} \
\hline
\end{array}$
-For the three types of media in Table 6.1, which medium (or media) is/are chemically defined?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  A and B 
E)  A and C 
A)  A 
B)  B 
C)  C 
D)  A and B 
E)  A and C

Question 14

Nitrogen-fixing bacteria, such as cyanobacteria, can use atmospheric nitrogen (N2) for their nitrogen source.

Accepted Answer

A) True 
 B)False

Question 15

Which of the following is an example of a metabolic activity that could be used to measure microbial growth?

Accepted Answer

A)  glucose consumption 
B)  most probable number (MPN) 
C)  direct microscopic count 
D)  turbidity 
E)  standard plate count 
A)  glucose consumption 
B)  most probable number (MPN) 
C)  direct microscopic count 
D)  turbidity 
E)  standard plate count

Question 16

An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell.

Accepted Answer

A) True 
 B)False

Question 17

Which of the following is an organic growth factor?

Accepted Answer

A)  vitamin B1 
B)  H2O 
C)  peptone 
D)  glucose 
E)  Mg+2 
A)  vitamin B1 
B)  H2O 
C)  peptone 
D)  glucose 
E)  Mg+2

Question 18

Most fungi grow best at pH

Accepted Answer

A)  7. 
B)  1. 
C)  14. 
D)  5. 
E)  9. 
A)  7. 
B)  1. 
C)  14. 
D)  5. 
E)  9.

Question 19

Salts and sugars work to preserve foods by creating a

Accepted Answer

A)  lower pH. 
B)  hypotonic environment. 
C)  lower osmotic pressure. 
D)  depletion of nutrients. 
E)  hypertonic environment. 
A)  lower pH. 
B)  hypotonic environment. 
C)  lower osmotic pressure. 
D)  depletion of nutrients. 
E)  hypertonic environment.

Question 20

Figure 6.2
  
-Figure 6.2 shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which section (or sections) shows a growth phase where the number of cells dying equals the number of cells dividing?

Accepted Answer

A)  a 
B)  b 
C)  c 
D)  d 
E)  a and c 
A)  a 
B)  b 
C)  c 
D)  d 
E)  a and c

Exam 6: Microbial Growth

Which of the following is NOT a direct method to measure microbial growth?

During which growth phase will gram-positive bacteria be most susceptible to penicillin?

Filtration methods, followed by growth of the bacteria trapped on the filters in growth media, are used to count bacteria present in very low concentrations, such as in lakes and streams.

Which of the following is an advantage of the standard plate count?

The biosafety level (BSL) for most introductory microbiology laboratories is

The addition of which of the following to a culture medium will neutralize acids?

Most pathogenic bacteria are thermophiles.

Which of the following is the best definition of generation time?

Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases.

The source of nutrients in nutrient agar is

Table 6.1 Three different culture media are shown below. Medium A Medium B Medium C Na2H PO4 Tide detergent Glucose KH2PO4 Na2HPO4 Peptone -For the three types of media in Table 6.1, which medium (or media) is/are chemically defined?

Nitrogen-fixing bacteria, such as cyanobacteria, can use atmospheric nitrogen (N2) for their nitrogen source.

Which of the following is an example of a metabolic activity that could be used to measure microbial growth?

An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell.

Which of the following is an organic growth factor?

Most fungi grow best at pH

Salts and sugars work to preserve foods by creating a

Figure 6.2 -Figure 6.2 shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which section (or sections) shows a growth phase where the number of cells dying equals the number of cells dividing?

The Microbial World and You

Chemical Principles

Observing Microorganisms Through a Microscope

Functional Anatomy of Prokaryotic and Eukaryotic Cells

Microbial Metabolism

The Control of Microbial Growth

Microbial Genetics

Biotechnology and Dna Technology

Classification of Microorganisms

The Prokaryotes: Domains Bacteria and Archaea

The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

Viruses, Viroids, and Prions

Principles of Disease and Epidemiology

Microbial Mechanisms of Pathogenicity

Innate Immunity: Nonspecific Defenses of the Host

Adaptive Immunity: Specific Defenses of the Host

Practical Applications of Immunology

Disorders Associated With the Immune System

Antimicrobial Drugs

Microbial Diseases of the Skin and Eyes

Microbial Diseases of the Nervous System

Microbial Diseases of the Cardiovascular and Lymphatic Systems

Microbial Diseases of the Respiratory System

Microbial Diseases of the Digestive System

Microbial Disease of the Urinary and Reproductive Systems

Environmental Microbiology

Applied and Industrial Microbiology

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