Chapter 7 The Control of Microbial Growth My Nursing Test Banks

Microbiology: An Introduction, 12e, (Tortora)

Chapter 7   The Control of Microbial Growth

7.1   Multiple-Choice Questions

1) Which of the following is the best method to sterilize heat-labile solutions?

A) dry heat

B) autoclave

C) membrane filtration

D) pasteurization

E) freezing

Answer:  C

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.5

2) Which of the following best describes the pattern of microbial death?

A) The cells in a population die at a constant rate.

B) All the cells in a culture die at once.

C) Not all of the cells in a culture are killed.

D) The pattern varies depending on the antimicrobial agent.

E) The pattern varies depending on the species.

Answer:  A

Section:  7.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.2

3) Which of the following chemical agents is used for sterilization?

A) alcohol

B) phenolics

C) ethylene oxide

D) chlorine

E) soap

Answer:  C

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

4) Which of the following substances is used for surgical hand scrubs?

A) phenol

B) chlorine bleach

C) chlorhexidine

D) soap

E) glutaraldehyde

Answer:  C

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

5) Which of the following pairs of terms is mismatched?

A) bacteriostatic kills vegetative bacterial cells

B) germicide kills microbes

C) virucide inactivates viruses

D) sterilant destroys all living microorganisms

E) fungicide kills yeasts and molds

Answer:  A

Section:  7.1

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.1

6) The antimicrobial activity of chlorine is due to which of the following?

A) the formation of hypochlorous acid

B) the formation of hydrochloric acid

C) the formation of ozone

D) the formation of a hypochlorite ion

E) disruption of the plasma membrane

Answer:  A

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.10

7) Which of the following regarding antimicrobial control agents is FALSE?

A) Contaminating organic debris such as blood or sputum decrease effectiveness.

B) Some agents kill by denaturing microbial cell proteins.

C) Some agents affect microbial cell membranes by dissolving lipids.

D) Silver is used for treating antibiotic-resistant bacteria.

E) Alcohols effectively inactivate nonenveloped viruses by attacking lipids.

Answer:  E

Section:  7.5

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.9

8) Which of the following does NOT achieve sterilization?

A) dry heat

B) pasteurization

C) autoclave

D) supercritical fluids

E) ethylene oxide

Answer:  B

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.4

9) Which of the following is a limitation of the autoclave?

A) It requires an excessively long time to achieve sterilization.

B) It cannot inactivate viruses.

C) It cannot kill endospores.

D) It cannot be used with heat-labile materials.

E) It cannot be used with glassware.

Answer:  D

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.4

10) An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n)

A) disinfectant.

B) antiseptic.

C) aseptic.

D) fungicide.

E) virucide.

Answer:  A

Section:  7.1

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.1

11) Application of heat to living cells can result in all of the following EXCEPT

A) breaking of hydrogen bonds.

B) alteration of membrane permeability.

C) denaturation of enzymes.

D) decreased thermal death time.

E) damage to nucleic acids.

Answer:  D

Section:  7.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.2

12) Which of the following disinfectants acts by disrupting the plasma membrane?

A) soaps

B) aldehydes

C) bisphenols

D) halogens

E) heavy metals

Answer:  C

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

13) Oxidizing agents include all of the following EXCEPT

A) chlorine.

B) glutaraldehyde.

C) hydrogen peroxide.

D) iodine.

E) ozone.

Answer:  B

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

14) Disinfection of water is achieved by all of the following EXCEPT

A) ozone.

B) UV radiation.

C) chlorine.

D) copper sulfate.

E) peracetic acid.

Answer:  E

Section:  7.4; 7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.7

Global Outcome:  5

15) All of the following substances are effective against nonenveloped viruses EXCEPT

A) alcohol.

B) chlorine.

C) ethylene oxide.

D) ozone.

E) None of the answers is correct; all of these are equally effective against nonenveloped viruses.

Answer:  A

Section:  7.5

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.9

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

A) lyophilization

B) nonionizing radiation

C) freezing

D) ionizing radiation

E) pasteurization

Answer:  C

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.5

Global Outcome:  5

17) Which concentration of ethanol is the most effective bactericide?

A) 100 percent

B) 70 percent

C) 50 percent

D) 40 percent

E) 30 percent

Answer:  B

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

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

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.

Answer:  E

Section:  7.6

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  5.4

Learning Outcome:  7.14

Global Outcome:  7

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

A) 63C for 30 minutes

B) 72C for 15 seconds

C) 140C for 4 seconds

D) They are equivalent treatments.

E) None of the answers is correct.

Answer:  D

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.4

20) Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?

A) autoclave

B) gamma radiation

C) microwaves

D) sunlight

E) ultraviolet radiation

Answer:  B

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.6

21) Which of the following regarding antimicrobial control agents is FALSE?

A) Contaminating organic debris such as blood or sputum will decrease effectiveness.

B) Some agents kill by denaturing microbial cell proteins.

C) Some agents affect microbial cell membranes by dissolving lipids.

D) Some agents are utilized as both an antiseptic and a disinfectant.

E) A true antimicrobial control agent is equally effective against both bacteria and viruses.

Answer:  E

Section:  7.3

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.3

Figure 7.1

A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170C. Plate counts were used to determine the number of endospores surviving at the time intervals shown.

22) In Figure 7.1, what is the thermal death time?

A) 150C

B) 60 minutes

C) 120 minutes

D) 100C

E) The answer cannot be determined based on the information provided.

Answer:  B

Section:  7.2

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.2a

Learning Outcome:  7.2

Global Outcome:  3

23) In Figure 7.1, the thermal death point for this culture is

A) 15 minutes.

B) 50C.

C) 30 minutes.

D) 170C.

E) The answer cannot be determined based on the information provided

Answer:  E

Section:  7.2

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.2a

Learning Outcome:  7.2

Global Outcome:  3

24) 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

A) 0 minutes.

B) 10 minutes.

C) 30 minutes.

D) 40 minutes.

E) 60 minutes.

Answer:  B

Section:  7.2

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.2a

Learning Outcome:  7.2

Global Outcome:  3

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

A) heat

B) radiation

C) certain chemicals

D) heat and radiation

E) heat, radiation, and some chemicals

Answer:  E

Section:  7.4; 7.5

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.6, 7.9

26) Which of the following pairs is mismatched?

A) Ag wound dressings

B) alcohols open wounds

C) CuSO4 algicide

D) H2O2 open wounds

E) organic acids food preservation

Answer:  B

Section:  7.5

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.9

Figure 7.2

Assume 109 E. coli cells/ml are in a flask.

27) Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

A) a

B) b

C) c

D) d

E) e

Answer:  B

Section:  7.4

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4; 7.2a

Learning Outcome:  7.4

Global Outcome:  3

28) Which graph in Figure 7.2 best depicts the effect of placing the culture at 7C at time x?

A) a

B) b

C) c

D) d

E) e

Answer:  D

Section:  7.4

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4, 7.2a

Learning Outcome:  7.5

Global Outcome:  3

Table 7.1

A disk-diffusion test using Staphylococcus gave the following results:

Disinfectant Zone of inhibition (mm)

A0

B2.5

C10

D5

29) In Table 7.1, which compound was the most effective against Staphylococcus?

A) A

B) B

C) C

D) D

E) The answer cannot be determined based on the information provided.

Answer:  C

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.1b

Learning Outcome:  7.8

Global Outcome:  3

30) In Table 7.1, which compound was the most effective against E. coli?

A) A

B) B

C) C

D) D

E) The answer cannot be determined based on the information provided.

Answer:  E

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.1b

Learning Outcome:  7.8

Global Outcome:  3

31) In Table 7.1, which compound was bactericidal?

A) A

B) B

C) C

D) D

E) The answer cannot be determined based on the information provided.

Answer:  E

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.1b

Learning Outcome:  7.8

Global Outcome:  3

32) Table 7.2

The fate of E. coli O157:H7 in apple cider held at 8C for 2 weeks,

with and without preservatives, is shown below:

Bacteria/ml

Cider only 2.2

Cider with potassium sorbate 2.0

Sodium benzoate 0

Potassium sorbate + sodium benzoate 0

In Table 7.2, which preservative is most effective?

A) potassium sorbate

B) sodium benzoate

C) potassium sorbate + sodium benzoate

D) no preservative

Answer:  B

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.1b

Learning Outcome:  7.9

Global Outcome:  3

33) An iodophor is a(n)

A) phenol.

B) agent that reduces oxygen.

C) quaternary ammonium compound.

D) form of formaldehyde.

E) iodine mixed with a surfactant.

Answer:  E

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.10

34) Ethylene oxide

A) is a good antiseptic.

B) is not sporicidal.

C) requires high heat to be effective.

D) is a sterilizing agent.

E) is the active chemical in household bleach.

Answer:  D

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.13

35) All of the following substances are used to preserve foods EXCEPT

A) biguanides.

B) nisin.

C) potassium sorbate.

D) sodium nitrite.

E) calcium propionate.

Answer:  A

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

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)

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

A) Doom

B) K.O.

C) Mortum

D) Sterl

E) The answer cannot be determined based on the information provided.

Answer:  A

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4; 7.1b

Learning Outcome:  7.8

Global Outcome:  3

37) In Table 7.3, which disinfectant was bactericidal?

A) Doom

B) K.O.

C) Mortum

D) Sterl

E) The answer cannot be determined based on the information provided.

Answer:  C

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4; 7.1b

Learning Outcome:  7.8

Global Outcome:  3

38) In Table 7.3, which disinfectant was most effective against Salmonella?

A) Doom

B) K.O.

C) Mortum

D) Sterl

E) The answer cannot be determined based on the information provided.

Answer:  E

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4; 7.1b

Learning Outcome:  7.8

Global Outcome:  3

39) All of the following are effective for destroying prions EXCEPT

A) boiling.

B) incineration.

C) NaOH + autoclaving at 134C.

D) proteases.

E) None of the answers are correct; each of these will destroy prions.

Answer:  A

Section:  7.6

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.14

40) Which of the following pairs is mismatched?

A) ionizing radiation hydroxyl radicals

B) ozone takes electrons from substances

C) plasma sterilization free radicals

D) supercritical fluids CO2

E) ultraviolet radiation desiccation

Answer:  E

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.6

41) All of the following are methods of food preservation EXCEPT

A) desiccation.

B) high pressure.

C) ionizing radiation.

D) microwaves.

E) osmotic pressure.

Answer:  D

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.5

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

A) filtration

B) lyophilization

C) desiccation

D) ionizing radiation

E) supercritical CO2

Answer:  C

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.5

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

A) bleach

B) boiling for one hour

C) hydrogen peroxide

D) oven at 121C for one hour

E) pressure cooker at 121C for 15 minutes

Answer:  E

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.4

44) Bone and tendons for transplant are decontaminated by

A) ethylene oxide.

B) glutaraldehyde.

C) peroxygens.

D) plasma sterilization.

E) supercritical fluids.

Answer:  E

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

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

A) gram-negative bacteria

B) gram-positive bacteria

C) mycobacteria

D) protozoan cysts

E) viruses with lipid envelopes

Answer:  A

Section:  7.6

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.14

46) The following is true of quarternary ammonium compounds EXCEPT

A) they are non-toxic at lower concentrations.

B) they are tasteless.

C) they are effective when combined with soaps.

D) they are stable.

E) they may be an ingredient in mouthwash.

Answer:  C

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.11

7.2   True/False Questions

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

Answer:  FALSE

Section:  7.1

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.1

2) Desiccation is a reliable form of sterilization.

Answer:  FALSE

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.5

3) The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature.

Answer:  TRUE

Section:  7.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.2

4) Pseudomonas has been found growing in quaternary ammonium compounds (quats).

Answer:  TRUE

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.3

Learning Outcome:  7.7

5) Moist heat destroys organisms by denaturing proteins.

Answer:  TRUE

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.4

6) Some antimicrobial chemicals are considered to be disinfectants and antiseptics.

Answer:  TRUE

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.10

7) The pH of the medium has no effect on the activity of the disinfectant being applied.

Answer:  FALSE

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.7

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

Answer:  FALSE

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.6

9) Autoclaving is the most effective method of moist heat sterilization.

Answer:  TRUE

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.4

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

Answer:  FALSE

Section:  7.4

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  3.4

Learning Outcome:  7.5

7.3   Essay Questions

1) 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 hr at 20C, 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?

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.3a

Learning Outcome:  7.8

Global Outcome:  3

2) Assume that you are responsible for decontaminating materials in a large hospital. How would you sterilize each of the following? Briefly justify your answers.

a. a mattress used by a patient with bubonic plague

b. intravenous glucose-saline solutions

c. used disposable syringes

d. tissues taken from patients

Section:  7.4; 7.5

Blooms Taxonomy:  Synthesis

ASMcue Outcome:  7.3a

Learning Outcome:  7.7

Global Outcome:  8

3) Table 7.5

The following results were obtained from a use-dilution test of two disinfectants. Cultures were inoculated into tubes containing varying concentrations of the disinfectants, incubated for 10 min. at 20C, and then transferred to growth media without disinfectant.

(+ = growth; = no growth)

In Table 7.5, which disinfectant is most effective? Against which group of bacteria is Disinfectant A most effective?

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  7.3a

Learning Outcome:  7.8

Global Outcome:  3

4) How is hydrogen peroxide antimicrobial?

Section:  7.5

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.9

Global Outcome:  8

5) 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?

Section:  7.4

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  3.4

Learning Outcome:  7.4

Global Outcome:  8

6) What are the advantages of gluteraldehyde compared to formaldehyde?

Section:  7.5

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4

Learning Outcome:  7.12

Global Outcome:  8

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

Section:  7.3

Blooms Taxonomy:  Analysis

ASMcue Outcome:  3.4; 7.3a

Learning Outcome:  7.3

Global Outcome:  8

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