Ch 7 Multiple Choice
Which concentration of ethanol is the most effective bactericide? A) 100% B) 70% C) 50% D) 40% E) 30%
70%
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
Mycobacteria
If you were preparing nutrient agar at home and didn't have an autoclave, what could you use to sterilize the nutrient agar? A) Bleach B) Boiling for 1 hour C) Hydrogen peroxide D) Oven at 121°C for 1 hour E) Pressure cooker at 121°C for 15 minutes
Pressure cooker (at 121°C for 15 minutes)
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 free O E) Disruption of the plasma membrane
The formation of hypochlorous acid
A classmate is trying to determine how a disinfectant might kill cells. You observed that when he spilled the disinfectant in your reduced litmus milk, the litmus turned blue again. You suggest to your classmate that a. the disinfectant might inhibit cell wall synthesis. b. the disinfectant might oxidize molecules. c. the disinfectant might inhibit protein synthesis. d. the disinfectant might denature proteins. e. he take his work away from yours.
b
Assume 109 E. coli cells/ml are in a flask. Which graph in Figure 7.3 best depicts the effect of placing the culture in an autoclave for 15 min. at time x? Figure 7.3 A) a B) b C) c D) d E) e
b
Which disinfectant(s) is (are) bactericidal? a. A, B, C, and D b. A, C, and D c. A only d. B only e. none of the above
b
Which of the following is most effective for sterilizing mattresses and plastic Petri dishes? a. chlorine b. ethylene oxide c. glutaraldehyde d. autoclaving e. nonionizing radiation
b
Which of the following is most likely to be bactericidal? a. membrane filtration b. ionizing radiation c. lyophilization (freeze-drying) d. deep-freezing e. all of the above
b
Which of the following is not a characteristic of quaternary ammonium compounds? a. bactericidal against gram-positive bacteria b. sporicidal c. amoebicidal d. fungicidal e. kills enveloped viruses
b
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
gamma radiation
Which of the following is NOT used to disinfect water? A) Ozone B) Gamma radiation C) Chlorine D) Copper sulfate E) Heat
heat
Which of the following will NOT inactivate endospores? A) Autoclave B) Chlorine dioxide C) High pressure D) Plasma E) Supercritical CO2
high pressure
Glutaraldehyde is considered one of the most effective disinfectants for hospital use. Which of the following statements about glutaraldehyde is false? A) Stains and corrodes B) Is safe to transport C) Acts rapidly D) Is not hampered by organic material E) Attacks all microorganisms
stains and corrodes
Which of these disinfectants acts by denaturing proteins? A) Alcohols B) Aldehydes C) Bisphenols D) Halogens E) Phenolics
bisphenols
Which of the following will NOT destroy prions? A) Boiling B) Incineration C) NaOH + autoclaving at 134°C D) Proteases E) All of the above destroy prions.
boiling
Assume that one culture is a freshly opened package of dried yeast with 0.1% moisture, another culture is the same yeast with 7.5% moisture, and the third culture is a package of yeast mixed with water. Each culture was exposed to 130°C in a hot-air oven. Which graph in Figure 7.1 most likely shows the yeast with 0.1% moisture? A) a B) b C) c D) a and b E) b and c
c
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. 23) In Figure 7.2, the thermal death point for this culture is A) 15 min. B) 50°C. C) 30 min. D) 170°C. E) Can't tell
can't tell
Which of the following is a limitation of the autoclave? A) Requires a long time to achieve sterilization B) Cannot inactivate viruses C) Cannot kill endospores D) Cannot be used with heat-labile materials E) Cannot be used with glassware
cannot be used with heat-labile materials
Which of the following does NOT directly result from application of heat? A) Breaking of hydrogen bonds B) Breaking of sulfhydryl bonds C) Denaturing of enzymes D) Cell lysis E) Damage to nucleic acids
cell lysis
Which of the following substances is used for surgical hand scrubs? A) Phenol B) Chlorine bleach C) Chlorhexidine D) Soap E) Glutaraldehyde
chlorhexidine
Which of the following substances can sterilize? A) Alcohol B) Phenolics C) Ethylene oxide D) Chlorine E) Soap
ethylene oxide
In Figure 7.2, the decimal reduction time (D value) for the culture is approximately A) 0 min. B) 15 min. C) 30 min. D) 45 min. E) 60 min.
15 min.
Place the following surfactants in order from the most effective to the least effective antimicrobial activity: 1-Soap 2-Acid-anionic detergent 3-Quats A) 1, 2, 3 B) 1, 3, 2 C) 2, 1, 3 D) 3, 2, 1 E) 3, 1, 2
3, 2, 1
In Figure 7.1, what is the thermal death time for culture (a)? A) 150°C B) 60 min C) 120 min D) 100°C E) Can't tell
60 min
In Figure 7.2, the thermal death time for this culture is A) 0 min. B) 10 min. C) 20 min. D) 40 min. E) 60 min.
60 min.
Which one of the following does NOT belong with the others? A) Acid-anionic detergents B) Benzoic acid C) Supercritical CO2 D) Pasteurization E) Peracetic acid
Acid-anionic detergents
The following data Table 7.3 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) Doom K.O. Dilution Initial Subculture Initial Subculture 1:16 - + + + 1:32 - + + + 1:64 - + + + 1:128 + + + + Mortum Sterl Dilution Initial Subculture Initial Subculture 1:16 - - - + 1:32 - + + + 1:64 + + + + 1:128 + + + + 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) Can't tell
Answer: A
The fate of E. coli O157:H7 in apple cider held at 8°C for 2 weeks, with and without preservatives, is shown below: Table 7.2 Bacteria/ml Cider only 2.2 Cider with potassium sorbate 2.0 Sodium benzoate 0 Sorbate + benzoate 0 32) In Table 7.2, which preservative is most effective? A) Sorbate B) Benzoate C) Sorbate + benzoate D) No preservative
Answer: B
A disk-diffusion test using Staphylococcus gave the following results: Table 7.1 Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 29) In Table 7.1, which compound was the most effective against Staphylococcus? A) A B) B C) C D) D E) Can't tell
Answer: C
The following data Table 7.3 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) Doom K.O. Dilution Initial Subculture Initial Subculture 1:16 - + + + 1:32 - + + + 1:64 - + + + 1:128 + + + + Mortum Sterl Dilution Initial Subculture Initial Subculture 1:16 - - - + 1:32 - + + + 1:64 + + + + 1:128 + + + + In Table 7.3, which disinfectant was bactericidal? A) Doom B) K.O. C) Mortum D) Sterl E) Can't tell
Answer: C
A disk-diffusion test using Staphylococcus gave the following results: Table 7.1 Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In Table 7.1, which compound was bactericidal? A) A B) B C) C D) D E) Can't tell
Answer: E
A disk-diffusion test using Staphylococcus gave the following results: Table 7.1 Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In Table 7.1, which compound was the most effective against E. coli? A) A B) B C) C D) D E) Can't tell
Answer: E
The following data Table 7.3 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) Doom K.O. Dilution Initial Subculture Initial Subculture 1:16 - + + + 1:32 - + + + 1:64 - + + + 1:128 + + + + Mortum Sterl Dilution Initial Subculture Initial Subculture 1:16 - - - + 1:32 - + + + 1:64 + + + + 1:128 + + + + In Table 7.3, which disinfectant was most effective against Salmonella? A) Doom B) K.O. C) Mortum D) Sterl E) Can't tell
Answer: E
Which of the following substances is NOT used to preserve foods? A) Biguanides B) Nisin C) Potassium sorbate D) Sodium nitrite E) Sodium propionate
Biguanides
Which graph in Figure 7.3 best depicts the effect of placing the culture at 7°C at time x? A) a B) b C) c D) d E) e
D
Which of the following substances is NOT an oxidizing agent? A) Chlorine B) Glutaraldehyde C) Hydrogen peroxide D) Iodine E) Ozone
Glutaraldehyde
Which one of the following does NOT belong with the others? A) Beta-propiolactone B) Glutaraldehyde C) Ethylene oxide D) Hydrogen peroxide E) Propylene oxide
Hydrogen peroxide
Bone and tendons for transplant are decontaminated by A) Ethylene oxide. B) Glutaraldehyde. C) Peroxygens. D) Plasma sterilization. E) Supercritical fluids.
Supercritical fluids
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.
The cells in a population die at a constant rate
Which one 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
Ultraviolet radiation - desiccation
Which disinfectant is the most effective?
a
Which of the following is used to control microbial growth in foods? a. organic acids b. alcohols c. aldehydes d. heavy metals e. all of the above
a
Which of the following substances is NOT effective against nonenveloped viruses? A) Alcohol B) Chlorine C) Ethylene oxide D) Ozone E) All are equally effective.
alcohol
Which of the following pairs is mismatched? A) Ag - burns B) Alcohols - open wounds C) CuSO4 - algicide D) H2O2 - open wounds E) Organic acids - food preservation
alcohols - open wounds
Which of the following treatments is the most effective for controlling microbial growth? A) 63°C for 30 min. B) 72°C for 15 sec. C) 140°C for 4 sec. D) all 3 are equivalent E) None is effective.
all 3 are equivalent
Iodophors differ from iodine (I2) in that iodophors A) Don't stain. B) Are less irritating. C) Are longer lasting. D) Are combined with a nonionic detergent. E) All of the above.
all of the above
Which of the following affects the elimination of bacteria from an object? A) Number of bacteria present B) Temperature C) pH D) Presence of organic matter E) All of the above
all of the above
Which of the following is NOT a factor contributing to hospital-acquired infections? 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) All of the above
all of the above
Which of the following cannot be used to sterilize a heat-labile solution stored in a plastic container? a. gamma radiation b. ethylene oxide c. supercritical f luids d. autoclaving e. short-wavelength radiation
d
Which of the following does not kill endospores? a. autoclaving b. incineration c. hot-air sterilization d. pasteurization e. All of the above kill endospores.
d
Which of these disinfectants does not act by disrupting the plasma membrane? a. phenolics b. phenol c. quats d. halogens e. biguanides
d
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
membrane filtration
Which of the following will NOT preserve foods? A) Desiccation B) High pressure C) Ionizing radiation D) Microwaves E) Osmotic pressure
microwaves
Which of the following does NOT achieve sterilization? A) Dry heat B) Pasteurization C) Autoclave D) Formaldehyde E) Ethylene oxide
pasteurization