Question 1

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

Accepted Answer

A) filtration 
B) lyophilization 
C) desiccation 
D) ionizing radiation 
E) supercritical CO₂ 
A) filtration 
B) lyophilization 
C) desiccation 
D) ionizing radiation 
E) supercritical CO₂ C

Question 2

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

Question 3

Table 7.3
The following data were obtained by incubating gram-positive bacteria in nutrient medium + disinfectant for 24 hours,then transferring one loopful to nutrient medium (subculturing).(+ = growth;- = no growth)
  
-In Table 7.3,which disinfectant was bactericidal?

Accepted Answer

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

Question 4

Table 7.1
A disk-diffusion test using Staphylococcus gave the following results:
 $$\begin{array} { c c } 
\text { Disinfectant } & \text { Zone of inhibition } ( \mathrm { mm } ) \
 \text { A } & 0 \
\text { B } & 2.5 \
\text { C } & 10 \
\text { D } & 5
\end{array}$$
-In Table 7.1,which compound was bactericidal?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) The answer cannot be determined based on the information provided. 
A) A 
B) B 
C) C 
D) D 
E) The answer cannot be determined based on the information provided.

Question 5

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 thermal death point for this culture is

Accepted Answer

A) 15 minutes. 
B) 50°C. 
C) 30 minutes. 
D) 170°C. 
E) The answer cannot be determined based on the information provided 
A) 15 minutes. 
B) 50°C. 
C) 30 minutes. 
D) 170°C. 
E) The answer cannot be determined based on the information provided

Question 6

Disinfection of water is achieved by all of the following EXCEPT

Accepted Answer

A) ozone. 
B) UV radiation. 
C) chlorine. 
D) copper sulfate. 
E) peracetic acid. 
A) ozone. 
B) UV radiation. 
C) chlorine. 
D) copper sulfate. 
E) peracetic acid.

Question 7

Which of the following chemical agents is used for sterilization?

Accepted Answer

A) alcohol 
B) phenolics 
C) ethylene oxide 
D) chlorine 
E) soap 
A) alcohol 
B) phenolics 
C) ethylene oxide 
D) chlorine 
E) soap

Question 8

One advantage of chemical plasma is that it ________ but a disadvantage is ________.

Accepted Answer

A) can be used to sterilize intricate surgical instruments such as a laproscope;cost 
B) cost;difficulty of implementing the procedure 
C) can be used for intricate surgical instruments;cannot be used on plastics 
D) can be used on many materials;the need for high temperature is damaging to some equipment 
E) destroys spores;cannot be used on plastics 
A) can be used to sterilize intricate surgical instruments such as a laproscope;cost 
B) cost;difficulty of implementing the procedure 
C) can be used for intricate surgical instruments;cannot be used on plastics 
D) can be used on many materials;the need for high temperature is damaging to some equipment 
E) destroys spores;cannot be used on plastics

Question 9

All of the following factors contribute to hospital-acquired infections EXCEPT

Accepted Answer

A) some bacteria metabolize disinfectants. 
B) gram-negative bacteria are often resistant to disinfectants. 
C) invasive procedures can provide a portal of entry for bacteria. 
D) bacteria may be present in commercial products such as mouthwash. 
E) None of the answers is correct;all of these factors may contribute to hospital-acquired infection. 
A) some bacteria metabolize disinfectants. 
B) gram-negative bacteria are often resistant to disinfectants. 
C) invasive procedures can provide a portal of entry for bacteria. 
D) bacteria may be present in commercial products such as mouthwash. 
E) None of the answers is correct;all of these factors may contribute to hospital-acquired infection.

Question 10

Some antimicrobial chemicals are considered to be disinfectants and antiseptics.

Accepted Answer

A) True 
 B)False

Question 11

Table 7.4
The results below were obtained from a use-dilution test of two disinfectants.Cultures were inoculated into tubes with varying concentrations of disinfectants and incubated for 24 hours at 20°C,then subcultured in nutrient media without disinfectants.
(+ = growth;- = no growth)
  
- In Table 7.4,what is the minimal bacteriostatic concentration of each disinfectant? Which compound is bactericidal? At what concentration?

Accepted Answer

Without the actual data from Table 7.4,

Question 12

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?

Accepted Answer

A) lyophilization 
B) nonionizing radiation 
C) freezing 
D) ionizing radiation 
E) pasteurization 
A) lyophilization 
B) nonionizing radiation 
C) freezing 
D) ionizing radiation 
E) pasteurization

Question 13

Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization.

Accepted Answer

A) True 
 B)False

Question 14

Ultraviolet light (UV)causes irreversible breaks in DNA strands.

Accepted Answer

A) True 
 B)False

Question 15

All of the following are methods of food preservation EXCEPT

Accepted Answer

A) desiccation. 
B) high pressure. 
C) ionizing radiation. 
D) microwaves. 
E) osmotic pressure. 
A) desiccation. 
B) high pressure. 
C) ionizing radiation. 
D) microwaves. 
E) osmotic pressure.

Question 16

List the microbial targets of disinfecting chemicals and provide one example of a chemical agent that affects that structure.

Accepted Answer

The microbial targets of disinfecting ch

Question 17

Why must most milk sold in the U.S.be refrigerated at all times while evaporated canned milk and milk in cardboard containers sold in Europe do not need to be refrigerated until they are opened?

Accepted Answer

The primary reason most milk sold in the

Question 18

Which concentration of ethanol is the most effective bactericide?

Accepted Answer

A) 100 percent 
B) 70 percent 
C) 50 percent 
D) 40 percent 
E) 30 percent 
A) 100 percent 
B) 70 percent 
C) 50 percent 
D) 40 percent 
E) 30 percent

Question 19

Microorganisms placed in high concentrations of salts and sugars undergo lysis.

Accepted Answer

A) True 
 B)False

Question 20

All of the following are effective for destroying prions EXCEPT

Accepted Answer

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

Exam 7: The Control of Microbial Growth

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

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?

Table 7.3 The following data were obtained by incubating gram-positive bacteria in nutrient medium + disinfectant for 24 hours,then transferring one loopful to nutrient medium (subculturing).(+ = growth;- = no growth) -In Table 7.3,which disinfectant was bactericidal?

Table 7.1 A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition () A 0 B 2.5 C 10 D 5 -In Table 7.1,which compound was bactericidal?

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 thermal death point for this culture is

Disinfection of water is achieved by all of the following EXCEPT

Which of the following chemical agents is used for sterilization?

One advantage of chemical plasma is that it ________ but a disadvantage is ________.

All of the following factors contribute to hospital-acquired infections EXCEPT

Some antimicrobial chemicals are considered to be disinfectants and antiseptics.

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?

Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization.

Ultraviolet light (UV)causes irreversible breaks in DNA strands.

All of the following are methods of food preservation EXCEPT

List the microbial targets of disinfecting chemicals and provide one example of a chemical agent that affects that structure.

Why must most milk sold in the U.S.be refrigerated at all times while evaporated canned milk and milk in cardboard containers sold in Europe do not need to be refrigerated until they are opened?

Which concentration of ethanol is the most effective bactericide?

Microorganisms placed in high concentrations of salts and sugars undergo lysis.

All of the following are effective for destroying prions EXCEPT

The Microbial World and You

Chemical Principles

Observing Microorganisms Through a Microscope

Functional Anatomy of Prokaryotic and Eukaryotic

Microbial Metabolism

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 Diseases of the Urinary and Reproductive Systems

Environmental Microbiology

Applied and Industrial Microbiology

Filters

One advantage of chemical plasma is that it but a disadvantage is .