Deck 9: Controlling Microbial Growth in the Environment

Question 1

All of the following are associated with filtration EXCEPT:

A) sterilization of heat- sensitive materials.
B) nitrocellulose or plastic membrane filters.
C) viruses and proteins can be trapped by some filters.
D) varying thicknesses of membrane filters used.
E) HEPA filters are used to filter air.

Answer 1

D

Question 2

Which of the following can be used to disinfect air?

A) HEPA filters
B) ethylene oxide
C) ultraviolet light
D) Both A and C are correct.
E) Both A and B are correct.

Answer 2

D

Question 3

All of the following sterilize EXCEPT:

A) incineration.
B) lyophilization.
C) autoclaving.
D) ionizing radiation.
E) dry heat.

Answer 3

B

Question 4

Which of the following has been incorporated into consumer products such as diapers and cutting boards?

A) hexachlorophene
B) peracetic acid
C) thimerosal
D) triclosan
E) ethylene oxide

Question 5

Which of the following is a true statement concerning microbial death?

A) It can be used to evaluate the efficacy of antimicrobial agents.
B) It speeds up over time of exposure to an antimicrobial agent.
C) It is the permanent loss of a microbe's reproductive ability.
D) Both A and C are correct.
E) A, B, and C are correct.

Question 6

Which of the following describes the batch method of pasteurization?

A) heating at 134°C for one second
B) heating at 63°C for 30 minutes
C) heating at 72°C for 15 minutes
D) heating at 72°C for 15 seconds
E) passing liquid through steam at 140°C

Question 7

All of the following are components of an autoclave EXCEPT:

A) membrane filters.
B) valves.
C) temperature gauges.
D) a pressure chamber.
E) pressure gauges.

Question 8

An instrument that will be used in an invasive medical procedure should be disinfected with a(n)

A) high- level germicide.
B) intermediate- level germicide.
C) low- level germicide.
D) Both A and C are correct.
E) A, B, and C are correct.

Question 9

Which of the following is used for microbial control in fresh fruits and vegetables?

A) ultraviolet light
B) electron beams
C) microwaves
D) X rays
E) gamma rays

Question 10

Which of the following is an example of sanitization?

A) A nurse prepares an injection site with an alcohol swab.
B) Heat is used to kill potential pathogens in apple juice.
C) A surgeon washes her hands before surgery.
D) An autoclave is used to prepare nutrient agar.
E) A public toilet is treated with disinfectants.

Question 11

The term "sterilization" applies to the removal of all of the following EXCEPT:

A) fungi.
B) prions.
C) viruses.
D) bacterial endospores.
E) bacterial cells.

Question 12

Which of the following is the least resistant to antimicrobial agents?

A) Gram- positive bacteria
B) bacterial endospores
C) protozoan cysts
D) enveloped viruses
E) protozoa

Question 13

Concerning alcohol, which of the following statements is false?

A) Isopropanol is a better disinfectant than ethanol.
B) One hundred percent alcohol is the most effective form.
C) Alcohols have more than one cellular target.
D) Alcohols are intermediate- level disinfectants.
E) Dissolving another chemical in alcohol is a good way to make it more effective.

Question 14

Which of the following is a target of pasteurization?

A) Brucella melitensis
B) Neisseria gonorrhoeae
C) Bacillus stearothermophilus
D) Chlamydia trachomatis
E) Clostridium botulinum

Question 15

Which of the following would NOT be bacteriostatic?

A) desiccation
B) freezing below 0°C
C) refrigeration of mesophiles
D) autoclaving
E) lyophilization

Question 16

Aseptic means

A) clean.
B) free of all microbes.
C) sterile.
D) free of all pathogens.
E) sanitized.

Question 17

Antimicrobial agents that interfere with nucleic acids also stop protein synthesis because

A) the ribosome contains ribozymes.
B) nucleic acids are involved in the production of proteins.
C) proteins are involved in the production of nucleic acids.
D) Both A and B are correct.
E) A, B, and C are correct.

Question 18

Which of the following is an example of degerming?

A) scrubbing your hands
B) canning fruits or vegetables
C) cleaning a public toilet
D) preparing your lab benchtop for work
E) using heat to make milk safe to drink

Question 19

All of the following statements concerning radiation as a method of microbial control are true EXCEPT:

A) UV light effectively kills cells but does not penetrate surfaces well.
B) electron beams have a lot of energy but do not penetrate substances very well.
C) microwaves are valuable in microbial control only when they are used to heat food.
D) X rays are the most practical form of ionizing radiation for microbial control.
E) gamma rays penetrate substances well but require hours to kill microbes.

Question 20

The dairy creamer used in restaurants is usually sterilized by

A) autoclaving.
B) UHT sterilization.
C) filtration.
D) ionizing radiation.
E) lyophilization.

Question 21

The spores of which of the following microbes are the most resistant to every known sterilization technique?

A) Bacillus stearothermophilus
B) Mycobacterium bovis
C) Clostridium botulinum
D) Neisseria gonorrhoeae
E) Pseudomonas aeruginosa

Question 22

Some viruses are inactivated by the same chemical or physical agents that damage cell membranes.

Question 23

All of the following are characteristics of aldehydes EXCEPT:

A) they are used in aqueous solutions.
B) some can sterilize after long periods of time.
C) they are used only to preserve dead tissues.
D) they are usually hazardous to humans.
E) they denature proteins.

Question 24

UV light of any wavelength creates pyrimidine dimers in DNA molecules.

Question 25

Boiling water rapidly kills all of the following EXCEPT:

A) protozoan cysts.
B) fungal cells.
C) protozoan trophozoites.
D) bacterial cells.
E) most viruses.

Question 26

All of the following have denaturing proteins included in their mechanism of action EXCEPT:

A) aldehydes.
B) oxidizing agents.
C) heavy metals.
D) gaseous agents.
E) surfactants.

Question 27

Which of the following is a sterilizing agent?

A) ozone
B) peracetic acid
C) hydrogen peroxide
D) Both A and C are correct.
E) A, B, and C are correct.

Question 28

A chemical agent that kills pathogenic microbes in general is a(n)

A) germicide.
B) fungicide.
C) antiseptic.
D) sanitizer.
E) disinfectant.

Question 29

Which of the following antimicrobial agents is the most toxic to humans?

A) quats
B) iodophors
C) ethylene oxide
D) chloramines
E) 70% alcohol

Question 30

Which of the following procedures is currently the standard test in the United States for evaluating the efficiency of antiseptics and disinfectants?

A) use- dilution test
B) microbial death rate
C) thermal death point
D) in- use test
E) phenol coefficient

Question 31

An environment may contain some microbes and still be considered sterile under certain conditions.

Question 32

The phenol coefficient is one of the most widely used measurements of an antimicrobial agent's effectiveness.

Question 33

Antimicrobial agents usually work best at high temperatures and pH levels.

Question 34

All of the following are characteristics of quaternary ammonium compounds EXCEPT:

A) Zephiran is an example of a quat.
B) they are harmless to humans except at high concentrations.
C) they are used by Pseudomonas aeruginosa as a nutrient.
D) they function by cross- linking proteins.
E) they are a type of detergent.

Question 35

Betadine is an example of which of the following?

A) halogens
B) surfactants
C) heavy metals
D) phenolics
E) alcohols

Question 36

Which of the following was used in the past to prevent the transmission of gonorrhea from an infected mother to her newborn?

A) silver nitrate
B) hydrogen peroxide
C) thimerosal
D) beta- propiolactone
E) hexachlorophene

Question 37

Which of the following is used to sterilize items that should not, or cannot, be exposed to heat or water?

A) ethylene oxide
B) calcium hypochlorite
C) hydrogen peroxide
D) formaldehyde
E) triclosan

Question 38

All of the following are characteristics of iodophors EXCEPT:

A) betadine is an example.
B) they are used as an antiseptic.
C) they are halogens.
D) they are inorganic molecules.
E) they have long- lasting effects.

Question 39

All of the following are characteristics of an ideal antimicrobial agent EXCEPT:

A) it denatures proteins.
B) it acts quickly.
C) it is harmless to humans.
D) it is stable during storage.
E) it is inexpensive.

Question 40

Which of the following would be used to sterilize a mattress?

A) heavy metals
B) radiation
C) formaldehyde
D) autoclaving
E) ethylene oxide

Question 41

The amount of time needed to sterilize materials using moist heat is (greater than/less than) the time needed to sterilize using dry heat.

Question 42

Natural antiseptics such as pine or clove oil are examples of antimicrobial compounds called _ .

Question 43

Elements such as iodine, chlorine, and bromine are examples of _ , which are the basis for many effective antimicrobial agents.

Question 44

is the process of drying foods such as fruits in order to preserve them from microbial growth.

Question 45

The decimal reduction time is the time required to kill all the microbes in a given sample.

Question 46

is the process of freeze- drying microbes to preserve them.

Question 47

Although they are excellent antimicrobial agents, must be used with care because they are often highly explosive.

Question 48

Slow freezing is more damaging to microbial cells than quick freezing.

Question 49

By themselves, soaps have only degerming activity, not antimicrobial activity.

Question 50

Human tears contain an antimicrobial enzyme called that digests bacterial cell walls.

Question 51

Ultraviolet light penetrates materials (better than/worse than) gamma rays.

Question 52

Sterilization procedures generally focus on the inactivation or elimination of bacterial .

Question 53

Gamma rays and X rays are examples of radiation.

Question 54

Antimicrobial chemicals produced naturally by microorganisms are called .

Question 55

Hypertonic environments inactivate microbial enzymes by removing water from cells.

Question 56

Ninety percent alcohol is more effective at denaturing protein than 100% alcohol.

Question 57

A(n) is an iodine- containing organic compound found in such antiseptics as Betadine.

Question 58

The lowest temperature that kills all cells in a broth in 10 minutes is known as the .

Question 59

The use of high levels of salt or sugar in the preservation of foods relies on the concept of .

Question 60

The is the time required to destroy 90% of the microbes in a sample.

Question 61

Some sterilization procedures do not kill all the microbes that may be present. Explain how these procedures can still be considered sterilization.

Question 62

Some antimicrobial agents that work by removal of microbes are just as effective as the agents that kill or inhibit these microbes. Explain why this is so, and give some examples of these types of agents.

Question 63

What is the in- use test, and why is it more useful than other methods of evaluating disinfectants?

Question 64

Describe the cellular structures or processes that can be targets of antimicrobial agents.

Question 65

Describe some factors that can either increase or decrease the effectiveness of antimicrobial agents.