CH 7
The preservation of beef jerky from microbial growth relies on which method of microbial control?
desiccation
Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?
freezing
Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?
gamma radiation
Oxidizing agents include all of the following EXCEPT
glutaraldehyde.
The antimicrobial activity of chlorine is due to which of the following?
the formation of hypochlorous acid
The following is true of quarternary ammonium compounds EXCEPT
they are effective when combined with soaps
Which one of the following is most resistant to chemical biocides?
gram-negative bacteria
All of the following are methods of food preservation EXCEPT
microwaves.
Bone and tendons for transplant are decontaminated by
supercritical fluids
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
10 minutes.
In Figure 7.1, what is the thermal death time?
60 minutes
Which concentration of ethanol is the most effective bactericide?
70 percent
Which of the following regarding antimicrobial control agents is FALSE?
A true antimicrobial control agent is equally effective against both bacteria and viruses.
Which of the following regarding antimicrobial control agents is FALSE?
Alcohols effectively inactivate nonenveloped viruses by attacking lipids.
Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?
B
In Table 7.1, which compound was the most effective against Staphylococcus?
C
Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?
D
In Table 7.3, which disinfectant is the most effective at stopping bacterial growth?
Doom
Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization.
FALSE
Desiccation is a reliable form of sterilization.
FALSE
Microorganisms placed in high concentrations of salts and sugars undergo lysis.
FALSE
The pH of the medium has no effect on the activity of the disinfectant being applied
FALSE
Ultraviolet light (UV) causes irreversible breaks in DNA strands.
FALSE
Which of the following is a limitation of the autoclave?
It cannot be used with heat-labile materials
In Table 7.3, which disinfectant was bactericidal?
Mortum
All of the following factors contribute to hospital-acquired infections EXCEPT
None of the answers is correct; all of these factors may contribute to hospital-acquired infection
Autoclaving is the most effective method of moist heat sterilization
TRUE
Moist heat destroys organisms by denaturing proteins.
TRUE
Pseudomonas has been found growing in quaternary ammonium compounds (quats).
TRUE
Some antimicrobial chemicals are considered to be disinfectants and antiseptics.
TRUE
The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature.
TRUE
In Figure 7.1, the thermal death point for this culture is
The answer cannot be determined based on the information provided
In Table 7.1, which compound was bactericidal?
The answer cannot be determined based on the information provided.
In Table 7.1, which compound was the most effective against E. coli?
The answer cannot be determined based on the information provided.
In Table 7.3, which disinfectant was most effective against Salmonella?
The answer cannot be determined based on the information provided.
Which of the following best describes the pattern of microbial death?
The cells in a population die at a constant rate
Which of the following treatments is the most effective for controlling microbial growth?
They are equivalent treatments
All of the following substances are effective against nonenveloped viruses EXCEPT
alcohol.
Which of the following pairs is mismatched?
alcohols — open wounds
Which of the following pairs of terms is mismatched?
bacteriostatic — kills vegetative bacterial cells
All of the following substances are used to preserve foods EXCEPT
biguanides.
Which of the following disinfectants acts by disrupting the plasma membrane?
bisphenols
All of the following are effective for destroying prions EXCEPT
boiling
Which of the following substances is used for surgical hand scrubs?
chlorhexidine
Application of heat to living cells can result in all of the following EXCEPT
decreased thermal death time.
An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n)
disinfectant.
Which of the following chemical agents is used for sterilization?
ethylene oxide
Which of the following results in lethal damage to nucleic acids?
heat, radiation, and some chemicals
An iodophor is a(n)
iodine mixed with a surfactant.
Ethylene oxide
is a sterilizing agent.
Which of the following is the best method to sterilize heat-labile solutions?
membrane filtration
Which of the following does NOT achieve sterilization?
pasteurization
Disinfection of water is achieved by all of the following EXCEPT
peracetic acid.
If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?
pressure cooker at 121°C for 15 minutes
In Table 7.2, which preservative is most effective?
sodium benzoate
Which of the following pairs is mismatched?
ultraviolet radiation — desiccation
