Micro- Chp. 5

A suffix used to describe a killing action would be A. -static. B. -cidal. C. -cillin. D. -tion.

-cidal.

In a one D process, how many D values would it take to reduce a population of 1010 cells to one survivor? A. 2 B. 4 C. 5 D. 10

10

Typical conditions used for sterilization are A. 100°C for 10 minutes. B. 121°C at 15 psi for 15 minutes. C. 80°C for 15 minutes. D. 72°C for 15 seconds.

121°C at 15 psi for 15 minutes.

If a process kills 90% of the organisms per minute, how many minutes would it take to kill all organisms when starting with 100,000 organisms? A. 1 minute B. 2 minutes C. 3 minutes D. 6 minutes

6 minutes

Chemical germicides A. may react irreversibly with proteins/enzymes. B. may react with cytoplasmic membranes or viral envelopes. C. may be disinfecting or even sterilizing. D. are sensitive to dilution factor, time of contact, and temperature of use. E. All of the choices are true.

All of the choices are true.

100% ethanol is twice as effective as 60% ethanol at controlling bacteria. True False

False

Cold and freezing are very effective in killing bacteria. True False

False

Dry heat takes a much shorter time to sterilize material than wet heat. True False

False

Heat treatment is an effective method for sterilization or disinfection of all materials. True False

False

Hydrogen peroxide may be used as a sterilant on living tissue. True False

False

Pasteurization results in the sterilization of food products. True False

False

Prions and viroids are easily destroyed by common sterilization procedures. True False

False

The endospores of Pseudomonas make that organism very difficult to kill. True False

False

Which of the following is true of hydrogen peroxide? A. It is a sterilant for inanimate objects and is quickly inactivated on living tissue. B. It leaves a toxic residue. C. It is broken down by catalase into water and oxygen. D. It is even more effective when used in combination with peracetic acid. E. It is a sterilant for inanimate objects and is quickly inactivated on living tissue; it is broken down by catalase into water and oxygen AND it is even more effective when used in combination with peracetic acid.

It is a sterilant for inanimate objects and is quickly inactivated on living tissue; it is broken down by catalase into water and oxygen AND it is even more effective when used in combination with peracetic acid.

A common environmental organism that may even grow in certain chemical disinfectants is A. Escherichia coli. B. Streptococcus pneumoniae. C. Pseudomonas aeruginosa. D. enveloped virus.

Pseudomonas aeruginosa.

Hexachlorophene has been particularly effective against A. Staphylococcus aureus. B. Micrococcus aureus. C. Escherichia coli. D. Enterobacter aerogenes.

Staphylococcus aureus.

Boiling is very effective at removing most common waterborne pathogens. True False

True

Generally, heavy metals, except silver, have been proven to be too toxic for use on human tissue and are no longer used medically. True False

True

Organic acids, such as benzoic acid, are often added to foods to prevent microbial growth. True False

True

The more bacteria ones starts with, the longer it will take to kill them all. True False

True

Upon heat treatment, bacteria die at a constant proportion. True False

True

Which of the following methods sterilize the materials? A. Pasteurization B. High-temperature-short-time pasteurization (HTST) C. Ultrahigh-temperature (UHT) method D. None of these are sterilization methods

Ultrahigh-temperature (UHT) method

for use on skin

antiseptic

Nosocomial infections A. are acquired at various social events. B. are acquired while in the hospital. C. occur because of a susceptible population and presence of disease causing organisms. D. are acquired at sporting events. E. are acquired while in the hospital AND occur because of a susceptible population and presence of disease causing organisms.

are acquired while in the hospital AND occur because of a susceptible population and presence of disease causing organisms.

Commercial canning processes A. are geared to destroy Clostridium botulinum spores. B. kill all endospores. C. are especially needed on low acid foods. D. are 12D processes. E. are geared to destroy Clostridium botulinum spores, are especially needed on low acid foods, AND are 12D processes.

are geared to destroy Clostridium botulinum spores, are especially needed on low acid foods, AND are 12D processes.

Gamma irradiation A. has not been approved for use on food. B. can be used to either sterilize or pasteurize, depending on the dose of radiation. C. leaves some radioactive particles in the treated substance. D. usually kills by disrupting cell membranes.

can be used to either sterilize or pasteurize, depending on the dose of radiation.

One of the first chemicals used by Lister to prevent surgical sepsis was A. alcohol. B. iodine. C. carbolic acid. D. mercury.

carbolic acid.

Quaternary ammonium compounds are A. cationic detergents which help wash surfaces. B. attracted to the negative charge on the microbial cell surface. C. used as a 37% aqueous solution. D. very effective against Pseudomonas. E. cationic detergents which help wash surfaces AND attracted to the negative charge on the microbial cell surface.

cationic detergents which help wash surfaces AND attracted to the negative charge on the microbial cell surface.

Ultraviolet radiation at the bactericidal wavelength destroy bacteria by A. destroying endospores. B. damaging nucleic acid. C. preventing spore formation. D. denaturing proteins.

damaging nucleic acid.

Phenolics A. denature proteins and destroy cytoplasmic membranes. B. remain effective in the presence of detergents or organic material. C. such as triclosan, have been used widely in various lotions and soaps. D. reliably inactivate all groups of viruses. E. denature proteins and destroy cytoplasmic membranes, remain effective in the presence of detergents or organic material, AND phenolics such as triclosan, have been used widely in various lotions and soaps.

denature proteins and destroy cytoplasmic membranes, remain effective in the presence of detergents or organic material, AND phenolics such as triclosan, have been used widely in various lotions and soaps.

Upon treatment with heat or chemicals, bacteria will A. all die immediately. B. die at a constant proportion. C. die at an exponential rate. D. die at a geometric rate.

die at a constant proportion.

use of heat to eliminate pathogens/spoilage organisms

disinfection

Which are essentially equivalent treatments? A. dry 200°C heat for 1.5 hours; wet 121°C heat for 15 minutes B. dry 160°C heat for 1.0 hours; wet 200°C heat for 30 minutes C. dry 121°C heat for 1.5 hours; wet 200°C heat for 15 minutes D. dry 100°C heat for 2.0 hours; wet 100°C heat for 30 minutes

dry 200°C heat for 1.5 hours; wet 121°C heat for 15 minutes

Generally, membrane filters are not used to remove A. bacteria from liquids. B. microorganisms from gases. C. spoilage agents from alcoholic beverages. D. enzymes.

enzymes.

Boiling is not reliable for sterilization because A. heat sensitive instruments may be destroyed. B. heat resistant endospores are unaffected. C. water boils at a higher temperature at lower altitudes. D. viruses are more sensitive to heat than bacteria.

heat resistant endospores are unaffected.

The autoclave treatment may be monitored by A. heat-sensitive tape. B. heat-resistant endospores of Geobacillus stearothermophilus. C. pressure indicators alone. D. waiting for contaminants to appear on freshly poured media. E. heat sensitive tape AND heat-resistant endospores of Bacillus stearothermophilus.

heat sensitive tape AND heat-resistant endospores of Bacillus stearothermophilus.

Oxidation of proteins is achieved most readily A. by moist heat. B. by moist heat under pressure. C. in a hot air oven. D. in the presence of organics.

in a hot air oven.

The most important function of nitrites in processed foods is to A. prevent browning. B. inhibit the germination of Clostridium botulinum endospores. C. prevent carcinogen formation. D. make the food more acidic.

inhibit the germination of Clostridium botulinum endospores.

Moist heat kills microorganisms by A. irreversible coagulation of proteins. B. destruction of carbohydrates in the cell wall. C. denaturation of nucleic acids. D. dissolving the capsule.

irreversible coagulation of proteins.

Ethylene oxide is gas that A. is very useful for sterilizing heat or moisture sensitive items. B. is potentially carcinogenic. C. is used as a 37% aqueous solution. D. is effective against all microorganisms except endospores and viruses. E. is very useful for sterilizing heat or moisture sensitive items AND is potentially carcinogenic.

is very useful for sterilizing heat or moisture sensitive items AND is potentially carcinogenic.

Liquid media containing heat-sensitive components would best be sterilized by A. Ultraviolet (UV) light at 500 nm B. freezing. C. lyophilization. D. membrane filtration.

membrane filtration.

A sterile item is free of A. microbes. B. endospores. C. viruses. D. prions. E. microbes, endospores AND viruses.

microbes, endospores AND viruses.

Alcohols are not reliably effective at destroying A. vegetative bacteria. B. enveloped viruses. C. naked viruses. D. endospores. E. naked viruses AND endospores.

naked viruses AND endospores.

Which of the following is not a sterilization method? A. hot air oven B. autoclave C. pasteurization D. filtration

pasteurization

elimination of most pathogens on a material

pasteurization

Gamma rays cause biological damage in living systems by A. producing reactive molecules such as superoxide and hydroxyl free radicals. B. causing tiny gravity sinks and black holes to be formed in the substance. C. introducing toxins. D. making the substance radioactive.

producing reactive molecules such as superoxide and hydroxyl free radicals.

Which would be most effective against Pseudomonas? A. alcohol B. radiation C. quaternary ammonium compounds

radiation

Chlorine A. readily reacts with organics to produce potentially carcinogenic trihalomethanes. B. is an effective, inexpensive, disinfectant able to destroy all types of microorganisms. C. is unaffected by the presence of organic material. D. is ineffective when diluted. E. readily reacts with organics to produce potentially carcinogenic trihalomethanes AND is an effective, inexpensive, disinfectant able to destroy all types of microorganisms.

readily reacts with organics to produce potentially carcinogenic trihalomethanes AND is an effective, inexpensive, disinfectant able to destroy all types of microorganisms.

reduction of microorganisms to meet health standards

sanitization

The process of killing or removing all the microorganisms in or on a material is termed A. sterilization. B. disinfection. C. sanitation. D. antisepsis.

sterilization

removal of all life

sterilization

A common application of dry heat in the laboratory is to A. prepare specimens for study. B. sterilize media. C. sterilize plastics. D. sterilize the inoculating loop.

sterilize the inoculating loop.

Microwaves do not kill organisms directly but kill by A. the heat they generate in a product. B. generating free radicals. C. generating toxins. D. creating thymine dimers.

the heat they generate in a product.

Compounds of tin, mercury, arsenic, and copper are no longer used to prevent microbial growth in cooling water primarily because A. antibiotics are cheaper. B. other chemicals were shown to be much more effective. C. microbes developed resistance to these metals. D. their use contributes to serious pollution of natural waters. E. All of the choices are correct.

their use contributes to serious pollution of natural waters.

In order to speed up the sterilization process, which of the following would be useful? A. drying the material B. washing/mechanical removal of bacteria/organic matter C. addition of organics D. nothing E. washing/mechanical removal of bacteria/organic matter AND addition of organics

washing/mechanical removal of bacteria/organic matter