Question 1

If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?

Accepted Answer

A)   oven at 121°C for one hour
B)   bleach
C)   pressure cooker at 121°C for 15 minutes
D)   boiling for one hour
E)   hydrogen peroxideF) B) and D)
G) A) and E)

Question 2

Desiccation is a reliable form of sterilization.

Accepted Answer

A) True 
 B)False

Question 3

Which one of the following is most resistant to chemical biocides?

Accepted Answer

A)   mycobacteria
B)   protozoan cysts
C)   gram-positive bacteria
D)   gram-negative bacteria
E)   viruses with lipid envelopesF) B) and E)
G) A) and B)

Question 4

Which of the following treatments is the most effective for controlling microbial growth?

Accepted Answer

A)   140°C for 4 seconds
B)   63°C for 30 minutes
C)   72°C for 15 seconds
D)   They are equivalent treatments.
E)   None of the answers is correct.F) A) and B)
G) C) and D)

Question 5

All of the following are effective for destroying prions EXCEPT

Accepted Answer

A)   boiling.
B)   NaOH + autoclaving at 134°C.
C)   proteases.
D)   incineration.
E)   None of the answers are correct; each of these will destroy prions.F) A) and C)
G) B) and C)

Question 6

Figure 7.1
  A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown.
-In Figure 7.1, what is the thermal death time?

Accepted Answer

A)   100°C
B)   120 minutes
C)   60 minutes
D)   150°C
E)   The answer cannot be determined based on the information provided.F) B) and E)
G) B) and D)

Question 7

The preservation of beef jerky from microbial growth relies on which method of microbial control?

Accepted Answer

A)   supercritical CO₂
B)   filtration
C)   desiccation
D)   ionizing radiation
E)   lyophilizationF) C) and D)
G) C) and E)

Question 8

Which of the following is a limitation of the autoclave?

Accepted Answer

A)   It cannot kill endospores.
B)   It cannot inactivate viruses.
C)   It cannot be used with glassware.
D)   It cannot be used with heat-labile materials.
E)   It requires an excessively long time to achieve sterilization.F) A) and B)
G) All of the above

Question 9

Oxidizing agents include all of the following EXCEPT

Accepted Answer

A)   iodine.
B)   glutaraldehyde.
C)   hydrogen peroxide.
D)   chlorine.
E)   ozone.F) B) and C)
G) A) and B)

Question 10

Figure 7.2
Assume 109 E. coli cells/ml are in a flask.
 
-Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

Accepted Answer

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

Question 11

Figure 7.1
  A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown.
-In Figure 7.1, the decimal reduction time (D value)  for the culture, which is defined as the time to reduce a population by one log, is approximately

Accepted Answer

A)   40 minutes.
B)   30 minutes.
C)   0 minutes.
D)   10 minutes.
E)   60 minutes.F) A) and B)
G) B) and C)

Question 12

Table 7.3
The following data were obtained by incubating gram -positive bacteria in nutrient medium + disinfectant for 24 hr, then transferring one loopful to nutrient medium (subculturing) . (+ = growth; - = no growth) 
   Dilution 1:161:321:641:128 Doom  Initial  Subculture −+−+−+++ K.O.  Initial  Subculture ++++++++ Dilution 1:161:321:641:128 Mortum  Initial  Subculture −−−+++++ sterl  Initial  Subculture ++++++++\begin{array} { l  } \begin{array}{r}	ext { Dilution } \1: 16 \1: 32 \1: 64 \1: 128\end{array}&\begin{array}{cc}{	ext { Doom }} \\hline 	ext { Initial } & 	ext { Subculture } \- & + \- & + \- & + \+ & +\end{array}&\begin{array}{cc}{	ext { K.O. }} \\hline 	ext { Initial } & 	ext { Subculture } \+ & + \+ & + \+ & + \+ & +\end{array}\\\begin{array}{r}	ext { Dilution } \1: 16 \1: 32 \1: 64 \1: 128\end{array}&\begin{array}{cc}{	ext { Mortum }} \\hline 	ext { Initial } & 	ext { Subculture } \- & - \- & + \+ & + \+ & +\end{array}&\begin{array}{cc}{	ext { sterl }} \\hline 	ext { Initial } & 	ext { Subculture } \+ & + \+ & + \+ & + \+ & +\end{array}\end{array} Dilution 1:161:321:641:128​ Dilution 1:161:321:641:128​​ Doom  Initial −−−+​ Subculture ++++​​ Mortum  Initial −−++​ Subculture −+++​​​ K.O.  Initial ++++​ Subculture ++++​​ sterl  Initial ++++​ Subculture ++++​​​

-In Table 7.3, which disinfectant is the most effective at stopping bacterial growth?

Accepted Answer

A)   Doom
B)   K.O.
C)   Mortum
D)   Sterl
E)   The answer cannot be determined based on the information provided. F) A) and B)
G) B) and D)

Question 13

Which of the following results in lethal damage to nucleic acids?

Accepted Answer

A)   heat
B)   radiation
C)   certain chemicals
D)   heat and radiation
E)   heat, radiation, and some chemicalsF) All of the above
G) A) and B)

Question 14

Figure 7.2
Assume 109 E. coli cells/ml are in a flask.
 
-Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?

Accepted Answer

A)   a
B)   b
C)   c
D)   d
E)   eF) None of the above
G) B) and D)

Question 15

An iodophor is a(n)

Accepted Answer

A)   iodine mixed with a surfactant.
B)   agent that reduces oxygen.
C)   quaternary ammonium compound.
D)   form of formaldehyde.
E)   phenol.F) A) and E)
G) A) and D)

Question 16

Disinfection of water is achieved by all of the following EXCEPT

Accepted Answer

A)   chlorine.
B)   copper sulfate.
C)   peracetic acid.
D)   ozone.
E)   UV radiation.F) A) and E)
G) All of the above

Exam 7: The Control of Microbial Growth

If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?

Correct Answer
verified

Which of the following results in lethal damage to nucleic acids?

Correct Answer
verified

All of the following are effective for destroying prions EXCEPT

Correct Answer
verified

Desiccation is a reliable form of sterilization.

Correct Answer
verified

Which of the following is a limitation of the autoclave?

Correct Answer
verified

Correct Answer
verified

Figure 7.1 A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown. -In Figure 7.1, what is the thermal death time?

Correct Answer
verified

Which one of the following is most resistant to chemical biocides?

Correct Answer
verified

Disinfection of water is achieved by all of the following EXCEPT

Correct Answer
verified

Which of the following treatments is the most effective for controlling microbial growth?

Correct Answer
verified

Oxidizing agents include all of the following EXCEPT

Correct Answer
verified

The preservation of beef jerky from microbial growth relies on which method of microbial control?

Correct Answer
verified

Figure 7.2 Assume 109 E. coli cells/ml are in a flask. -Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

Correct Answer
verified

An iodophor is a(n)

Correct Answer
verified

Figure 7.2 Assume 109 E. coli cells/ml are in a flask. -Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?

Correct Answer
verified

Correct Answer
verified

Exam 7: The Control of Microbial Growth

If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?

Correct AnswerverifiedShow Answer

Which of the following results in lethal damage to nucleic acids?

Correct AnswerverifiedShow Answer

All of the following are effective for destroying prions EXCEPT

Correct AnswerverifiedShow Answer

Desiccation is a reliable form of sterilization.

Correct AnswerverifiedShow Answer

Which of the following is a limitation of the autoclave?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Figure 7.1 A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown. -In Figure 7.1, what is the thermal death time?

Correct AnswerverifiedShow Answer

Which one of the following is most resistant to chemical biocides?

Correct AnswerverifiedShow Answer

Disinfection of water is achieved by all of the following EXCEPT

Correct AnswerverifiedShow Answer

Which of the following treatments is the most effective for controlling microbial growth?

Correct AnswerverifiedShow Answer

Oxidizing agents include all of the following EXCEPT

Correct AnswerverifiedShow Answer

The preservation of beef jerky from microbial growth relies on which method of microbial control?

Correct AnswerverifiedShow Answer

Figure 7.2 Assume 109 E. coli cells/ml are in a flask. -Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

Correct AnswerverifiedShow Answer

An iodophor is a(n)

Correct AnswerverifiedShow Answer

Figure 7.2 Assume 109 E. coli cells/ml are in a flask. -Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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