Microbio Chapter 7
In the figure, the decimal reduction time (D value) for the culture is approximately -30 minutes -40 minutes -60 minutes -10 minutes -0 minutes
10 minutes
In the figure, what is the thermal death time? -120 minutes -100°C -60 minutes -150°C -The answer cannot be determined
60 minutes
Which concentration of ethanol is the most effective bactericide? -100% -70% -50% -40% -30%
70%
Which of the following regarding antimicrobial control agents is false? -Some agents kill by denaturing microbial cell proteins -A true antimicrobial control agent is equally effective against both bacteria and viruses -Contaminating organic debris such as blood or sputum will decrease effectiveness -Some agents are utilized as both an antiseptic and a disinfectant -Some agents affect microbial cell membranes by dissolving lipids
A true antimicrobial control agent is equally effective against both bacteria and viruses
All of the following substances are effective against nonenveloped viruses EXCEPT -ethylene oxide -alcohol -ozone -chlorine -All are equally effective against nonenveloped viruses
Alcohol
Which of the following pairs is mismatched? -Ag wound dressings -organic acids food preservation -alcohols open wounds -H2O2 open wounds -CuSO4 algicide
Alcohols open wounds
Which graph in the figure best depicts the effect of placing the culture in an autoclave for 15 minutes at time x? -a -b -c -d -e
B
Which of the following pairs of terms is mismatched? -fungicide kills yeasts and molds -virucide - inactivates viruses -sterilant destroys all living microorganisms -germicide - kills microbes -bacteriostatic kills vegetative bacterial cells
Bacteriostatic kills vegetative bacterial cells
All of the following substances are used to preserve foods EXCEPT -nisin -potassium sorbate -biguanides -sodium nitrite -calcium propionate
Biguanides
All of the following are effective for destroying prions EXCEPT -proteases -NaOH + autoclaving at 134°C -boiling -incineration -Each of the answers will destroy prions
Boiling
A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In the table, which compound was the most effective against Staphylococcus? -A -B -C -D -The answer cannot be determined
C
Which graph in the figure best depicts the effect of placing the culture at 7°C at time x? -a -b -c -d -e
D: straight line
Application of heat to living cells can result in all of the following EXCEPT -decreased thermal death time -denaturation of enzymes -breaking of hydrogen bonds -alteration of membrane permeability -damage to nucleic acids
Decreased thermal death time
The preservation of beef jerky from microbial growth relies on which method of microbial control? -supercritical CO2 -desiccation -ionizing radiation -filtration -lyophilization
Desiccation
An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n) -antiseptic -fungicide -virucide -aseptic -disinfectant
Disinfectant
Which of the following chemical agents is used for sterilization? -ethylene oxide -soap -phenolics -alcohol -chlorine
Ethylene oxide
Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper? -sunlight -ultraviolet radiation -autoclave -microwaves -gamma radiation
Gamma radiation
Oxidizing agents include all of the following EXCEPT -hydrogen peroxide -glutaraldehyde -iodine -chlorine -ozone
Glutaraldehyde
Which of the following results in lethal damage to nucleic acids? -heat -radiation -certain chemicals -heat and radiation -heat, radiation, and some chemicals
Heat, radiation, and some chemicals
An iodophor is a(n) -form of formaldehyde -quaternary ammonium compound -iodine mixed with a surfactant -agent that reduces oxygen -phenol
Iodine mixed with a surfactant
Which of the following is a limitation of the autoclave? -It requires an excessively long time to achieve sterilization -It cannot inactivate viruses -It cannot kill endospores -It cannot be used with glassware -It cannot be used with heat-labile materials
It cannot be used with heat-labile materials
Which of the following is the best method to sterilize heat-labile solutions? -membrane filtration -dry heat -pasteurization -autoclave -freezing
Membrane filtration
All of the following are methods of food preservation EXCEPT -high pressure -ionizing radiation -desiccation -osmotic pressure -microwaves
Microwaves
Which one of the following is most resistant to chemical biocides? -protozoan cysts -gram-negative bacteria -gram-positive bacteria -viruses with lipid envelopes -mycobacteria
Mycobacteria
Which of the following does NOT achieve sterilization? -pasteurization -autoclave -supercritical fluids -dry heat -ethylene oxide
Pasteurization
If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar? -hydrogen peroxide -oven at 121°C for 1 hour -boiling for 1 hour -pressure cooker at 121°C for 15 minutes -bleach
Pressure cooker at 121°C for 15 minutes
The fate of E. coli O157:H7 in apple cider held at 8°C 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 the table, which preservative is most effective? -potassium sorbate -sodium benzoate -potassium sorbate + sodium benzoate -no preservative
Sodium benzoate
Which of the following regarding antimicrobial control agents is false? -Contaminating organic debris such as blood or sputum decrease effectiveness -Some agents affect microbial cell membranes by dissolving lipids -Some agents inactivate viruses by attacking cell membrane lipids -Silver is used for treating antibiotic-resistant bacteria -Some agents kill by denaturing microbial cell proteins
Some agents inactivate viruses by attacking cell membrane lipids
Bone and tendons for transplant are decontaminated by -ethylene oxide -glutaraldehyde -plasma sterilization -peroxygens -supercritical fluids
Supercritical fluids
A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In the table, which compound was bactericidal? -A -B -C -D -The answer cannot be determined
The answer cannot be determined
A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In the table, which compound was the most effective against E. coli? -A -B -C -D -The answer cannot be determined
The answer cannot be determined
In the table, which disinfectant was bactericidal? -Aotus -Gorb -Tula -Komodo -The answer cannot be determined
The answer cannot be determined
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) 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 the table, which disinfectant was most effective against Salmonella? -Doom -K.O. -Sterl -Mortum -The answer cannot be determined
The answer cannot be determined
The antimicrobial activity of chlorine is due to which of the following? -the formation of hydrochloric acid -the formation of ozone -disruption of the plasma membrane -the formation of a hypochlorite ion -the formation of hypochlorous acid
The formation of hypochlorous acid
Which of the following treatments is the most effective for controlling microbial growth? -63°C for 30 minutes -72°C for 15 seconds -140°C for 4 seconds -They are equivalent treatments -None of the answers is correct
They are equivalent treatments
In the table, which disinfectant is the most effective at stopping bacterial growth? -Tula -Gorb -Aotus -Komodo -The answer cannot be determined
Tula