Microbiology Chapter 7

True or false Microorganisms placed in high concentrations of salts and sugars undergo lysis.

false

True or false The pH of the medium has no effect on the activity of the disinfectant being applied.

false

True or false Ultraviolet light (UV) causes irreversible breaks in DNA strands.

false

Which of the following methods is used to preserve food by slowing the metabolic processes of food born 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

Which of the following best describes the pattern of microbial death?

the cells in a population die at a constant rate

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 of the following treatments is the most effective for controlling microbial growth?

they are equivalent treatments

Which 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 table 7.3, which disinfectant was most effective against Salmonella?

the answer cannot be determined based on the information provided

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

A suspension of 106 Bacillus 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 701, what is the thermal death time?

60 minutes

Which concentration of ethanol is the most effective bactericide?

70 Percent

A disk-diffusion test using Stapylococcus gave the following results: A0 B2.5 C10 D5 In table 7.1, which compound was the most effective against Staphylococcus?

C: C10

In table 7.3, which disinfectant is the most effective at stopping bacterial growth?

Doom

Which graph in figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

Graph B

Which graph in figure 7.2 best depicts the effect of placing the culture at 7C at time x?

Graph D

In table 7.3, which disinfectant was bactericidal?

Mortum

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

Ethylene oxide is?

a sterilizing agent

Which of the following regarding antimicrobial control agents is FALSE?

a true antimicrobial control agent is equally effective against both bacteria and viruses

All of the following substances are effective against nonenveloped viruses EXCEPT?

alcohol

Which of the following regarding antimicrobial control agents is false?

alcohols effectively inactivate nonenveloped viruses by attacking lipids

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 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

The preservation of beef jerky from microbial growth relies on which method of microbial control?

desiccation

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

True or false Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization.

false

True or false Desiccation is a reliable form of sterilization.

false

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

Which of the following is a limitation of the autoclave?

it cannot be used with heat-labile materials

Which of the following is the best method to sterilize heat-labile solutions?

membrane filtration

All of the following factors contribute to hospital-acquired infections EXCEPT?

non of the answers is correct; all of these factors may contribute to hospital-acquired infections

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 121C for 15 minutes

In table 7.2, which preservative is most effective?

sodium benzoate

True or false Autoclaving is the most effective method of moist heat sterilization.

true

True or false Moist heat destroys organisms by denaturing proteins.

true

True or false Pseudomonas has been found growing in quaternary ammonium compounds (quats).

true

True or false Some antimicrobial chemicals are considered to be disinfectants and antiseptics.

true

True or false The thermal death time is the time needed to kill all bacteria in particular culture at a certain temperature.

true

Which of the following pairs is msimatched?

ultraviolet radiation desiccation