Chapter 7
disinfectant.
An agent used to reduce the number of bacteria on a toilet would most accurately be called an
iodine mixed with a surfactant
An iodophor is a(n)
60 minutes
A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170C. Plate counts were used to determine the number of endospores surviving at the time intervals shown. In Figure 7.1, what is the thermal death time?
pressure cooker at 121C for 15 minutes
If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?
10 minutes.
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
The answer cannot be determined based on the information provided
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?
Mortum
In Table 7.3, which disinfectant was bactericidal?
The answer cannot be determined based on the information provided.
In Table 7.3, which disinfectant was most effective against Salmonella?
C) C
Table 7.1 A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A0 B2.5 C10 D5 In Table 7.1, which compound was the most effective against Staphylococcus?
sodium benzoate
Table 7.2 The fate of E. coli O157:H7 in apple cider held at 8C 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 Table 7.2, which preservative is most effective?
A) Doom
Table 7.3 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) In Table 7.3, which disinfectant is the most effective at stopping bacterial growth?
chlorhexidine
Which of the following substances is used for surgical hand scrubs?
They are equivalent treatments.
Which of the following treatments is the most effective for controlling microbial growth?
gram-negative bacteria
Which one of the following is most resistant to chemical biocides?
biguanides.
All of the following substances are used to preserve foods EXCEPT
heat, radiation, and some chemicals
Which of the following results in lethal damage to nucleic acids?
None of the answers is correct; all of these factors may contribute to hospital-acquired infection.
All of the following factors contribute to hospital-acquired infections EXCEPT
alcohol.
All of the following substances are effective against nonenveloped viruses EXCEPT
boiling.
All of the following are effective for destroying prions EXCEPT
microwaves.
All of the following are methods of food preservation EXCEPT
decreased thermal death time.
Application of heat to living cells can result in all of the following EXCEPT
supercritical fluids.
Bone and tendons for transplant are decontaminated by
peracetic acid.
Disinfection of water is achieved by all of the following EXCEPT
is a sterilizing agent
Ethylene oxide
B) b
Figure 7.2 Assume 109 E. coli cells/ml are in a flask Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?
pressure cooker at 121C for 15 minutes
If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?
glutaraldehyde.
Oxidizing agents include all of the following EXCEPT
the formation of hypochlorous acid
The antimicrobial activity of chlorine is due to which of the following?
they are effective when combined with soaps
The following is true of quarternary ammonium compounds EXCEPT
desiccation
The preservation of beef jerky from microbial growth relies on which method of microbial control?
desiccation
The preservation of beef jerky from microbial growth relies on which method of microbial control?
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 of the following regarding antimicrobial control agents is FALSE?
70 percent
Which concentration of ethanol is the most effective bactericide?
D) d
Which graph in Figure 7.2 best depicts the effect of placing the culture at 7C at time x?
The cells in a population die at a constant rate.
Which of the following best describes the pattern of microbial death?
ethylene oxide
Which of the following chemical agents is used for sterilization?
gamma radiation
Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?
bisphenols
Which of the following disinfectants acts by disrupting the plasma membrane?
pasteurization
Which of the following does NOT achieve sterilization?
It cannot be used with heat-labile materials.
Which of the following is a limitation of the autoclave?
membrane filtration
Which of the following is the best method to sterilize heat-labile solutions?
freezing
Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?
alcohols open wounds
Which of the following pairs is mismatched?
ultraviolet radiation desiccation
Which of the following pairs is mismatched?
bacteriostatic kills vegetative bacterial cells
Which of the following pairs of terms is mismatched?
