Which of the following is the best method to sterilize heat-labile solutions?A) Dry heatB) AutoclaveC) Membrane filtrationD) PasteurizationE) Freezing
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.
Which of the following substances can sterilize?A) AlcoholB) PhenolicsC) Ethylene oxideD) ChlorineE) Soap
Which of the following substances is used for surgical hand scrubs?A) PhenolB) Chlorine bleachC) ChlorhexidineD) SoapE) Glutaraldehyde
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, 3B) 1, 3, 2C) 2, 1, 3D) 3, 2, 1E) 3, 1, 2
The antimicrobial activity of chlorine is due to which of the following?A) The formation of hypochlorous acidB) The formation of hydrochloric acidC) The formation of ozoneD) The formation of free OE) Disruption of the plasma membrane
Iodophors differ from iodine (I2) in that iodophorsA) Don't stain.B) Are less irritating.C) Are longer lasting.D) Are combined with a nonionic detergent.E) All of the above.
Which of the following does NOT achieve sterilization?A) Dry heatB) PasteurizationC) AutoclaveD) FormaldehydeE) Ethylene oxide
Which of the following is a limitation of the autoclave?A) Requires a long time to achieve sterilizationB) Cannot inactivate virusesC) Cannot kill endosporesD) Cannot be used with heat-labile materialsE) Cannot be used with glassware
Which of the following affects the elimination of bacteria from an object?A) Number of bacteria presentB) TemperatureC) pHD) Presence of organic matterE) All of the above
Which of the following does NOT directly result from application of heat?A) Breaking of hydrogen bondsB) Breaking of sulfhydryl bondsC) Denaturing of enzymesD) Cell lysisE) Damage to nucleic acids
Which of these disinfectants acts by denaturing proteins?A) AlcoholsB) AldehydesC) BisphenolsD) HalogensE) Phenolics
Which of the following substances is NOT an oxidizing agent?A) ChlorineB) GlutaraldehydeC) Hydrogen peroxideD) IodineE) Ozone
Which of the following is NOT used to disinfect water?A) OzoneB) Gamma radiationC) ChlorineD) Copper sulfateE) Heat
Which of the following substances is NOT effective against nonenveloped viruses?A) AlcoholB) ChlorineC) Ethylene oxideD) OzoneE) All are equally effective.
Glutaraldehyde is considered one of the most effective disinfectants for hospital use. Which of the following statements about glutaraldehyde is false?A) Stains and corrodesB) Is safe to transportC) Acts rapidlyD) Is not hampered by organic materialE) Attacks all microorganisms
Which concentration of ethanol is the most effective bactericide?A) 100%B) 70% C) 50%D) 40%E) 30%
18) 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 may contribute to hospital-acquired infection.
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) They are equivalent treatments.E) None is effective.
Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?A) AutoclaveB) Gamma radiationC) MicrowavesD) SunlightE) Ultraviolet radiation
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) aB) bC) cD) a and bE) b and c
Which of the following pairs is mismatched?A) Ag – burnsB) Alcohols – open woundsC) CuSO4 – algicideD) H2O2 – open woundsE) Organic acids – food preservation
Which one of the following does NOT belong with the others?A) Acid-anionic detergentsB) Benzoic acidC) Supercritical CO2D) PasteurizationE) Peracetic acid
Which one of the following does NOT belong with the others?A) Beta-propiolactoneB) GlutaraldehydeC) Ethylene oxideD) Hydrogen peroxideE) Propylene oxide
Which of the following substances is NOT used to preserve foods?A) BiguanidesB) NisinC) Potassium sorbateD) Sodium nitriteE) Sodium propionate
Which of the following will NOT destroy prions?A) BoilingB) IncinerationC) NaOH + autoclaving at 134°CD) ProteasesE) All of the above destroy prions.
Which one of the following pairs is mismatched?A) Ionizing radiation – hydroxyl radicalsB) Ozone – takes electrons from substancesC) Plasma sterilization – free radicalsD) Supercritical fluids – CO2E) Ultraviolet radiation – desiccation
Which of the following will NOT preserve foods?A) DesiccationB) High pressureC) Ionizing radiationD) MicrowavesE) Osmotic pressure
Which of the following will NOT inactivate endospores?A) AutoclaveB) Chlorine dioxideC) High pressureD) PlasmaE) Supercritical CO2
If you were preparing nutrient agar at home and didn’t have an autoclave, what could you use to sterilize the nutrient agar?A) BleachB) Boiling for 1 hourC) Hydrogen peroxideD) Oven at 121°C for 1 hourE) Pressure cooker at 121°C for 15 minutes
Bone and tendons for transplant are decontaminated byA) Ethylene oxide.B) Glutaraldehyde.C) Peroxygens.D) Plasma sterilization.E) Supercritical fluids.
Which one of the following is most resistant to chemical biocides?A) Gram-negative bacteriaB) Gram-positive bacteriaC) MycobacteriaD) Protozoan cystsE) Viruses with lipid envelopes
Which of the following does not kill endospores?
c) hot-air sterilization
e) all of the above kill endospores
Which of the following is most effective for sterilizing mattresses and plastic Petri dishes?
b) enthylene oxide
e) nonionizing radiation
Which of these disinfectants does not act by disrupting the plasma membrane?
c) quaternary ammonium compounds
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 fluids
e) short-wavelength radiation
Which of the following is not a characteristic of quaternary ammonium compounds?
a) bactericidal against gram-positive bacteria
e) kills enveloped viruses
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 denature proteins
d) the disinfectant might denature proteins
e) he take his work away from yours
Which of the following is most likely to be bactericidal?
a) membrane filtration
b) ionizing radiation
c) lyophilization (freeze-drying)
e) all of the above
Which of the following is used to control microbial growth in foods?
a) organic acids
d) heavy metals
e) all of the above