BIO 275 Quiz 7

oxidation

dry heat sterilization kills by ________

63 C for 30 minutes

equivalent treatments to high temperature short time and ultra high temperature

72 c for 15 seconds

high-temperature short-time (HTST)

flaming; incineration; hot-air sterilization

3 types of dry heat sterilization

boiling; free-flowing steam; autoclave

3 types of moist heat sterilization

number of microbes; environment; time of exposure; microbial characteristics

4 things that effectiveness of treatment depends on

boiling

All of the following are effective for destroying prions EXCEPT A) boiling. B) incineration. C) NaOH + autoclaving at 134°C. D) proteases. E) None of the answers are correct; each of these will destroy prions.

microwaves

All of the following are methods of food preservation EXCEPT A) desiccation. B) high pressure. C) ionizing radiation. D) microwaves. E) osmotic pressure.

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 A) some bacteria metabolize disinfectants. B) gram-negative bacteria are often resistant to disinfectants. C) invasive procedures can provide a portal of entry for bacteria. D) bacteria may be present in commercial products such as mouthwash. E) None of the answers is correct; all of these factors may contribute to hospital-acquired infection.

alcohol

All of the following substances are effective against nonenveloped viruses EXCEPT A) alcohol. B) chlorine. C) ethylene oxide. D) ozone. E) None of the answers is correct; all of these are equally effective against nonenveloped viruses.

biguanides

All of the following substances are used to preserve foods EXCEPT A) biguanides. B) nisin. C) potassium sorbate. D) sodium nitrite. E) calcium propionate.

disinfectant

An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n) A) disinfectant. B) antiseptic. C) aseptic. D) fungicide. E) virucide.

iodine mixed with a surfactant

An iodophor is a(n) A) phenol. B) agent that reduces oxygen. C) quaternary ammonium compound. D) form of formaldehyde. E) iodine mixed with a surfactant.

decreased thermal death time

Application of heat to living cells can result in all of the following EXCEPT A) breaking of hydrogen bonds. B) alteration of membrane permeability. C) denaturation of enzymes. D) decreased thermal death time. E) damage to nucleic acids.

supercritical fluids

Bone and tendons for transplant are decontaminated by A) ethylene oxide. B) glutaraldehyde. C) peroxygens. D) plasma sterilization. E) supercritical fluids.

peracetic acid

Disinfection of water is achieved by all of the following EXCEPT A) ozone. B) UV radiation. C) chlorine. D) copper sulfate. E) peracetic acid.

is a sterilizing agent

Ethylene oxide A) is a good antiseptic. B) is not sporicidal. C) requires high heat to be effective. D) is a sterilizing agent. E) is the active chemical in household bleach.

pressure cooker at 121 c 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? A) bleach B) boiling for one hour C) hydrogen peroxide D) oven at 121°C for one hour E) pressure cooker at 121°C for 15 minutes

glutaraldehyde

Oxidizing agents include all of the following EXCEPT A) chlorine. B) glutaraldehyde. C) hydrogen peroxide. D) iodine. E) ozone.

the formation of hypochlorous acid

The antimicrobial activity of chlorine is due to which of the following? A) the formation of hypochlorous acid B) the formation of hydrochloric acid C) the formation of ozone D) the formation of a hypochlorite ion E) disruption of the plasma membrane

desiccation

The preservation of beef jerky from microbial growth relies on which method of microbial control? A) filtration B) lyophilization C) desiccation D) ionizing radiation E) supercritical CO2

70 percent

Which concentration of ethanol is the most effective bactericide? A) 100 percent B) 70 percent C) 50 percent D) 40 percent E) 30 percent

the cells in a population die at a constant rate

Which of the following best describes the pattern of microbial death? A) The cells in a population die at a constant rate. B) All the cells in a culture die at once. C) Not all of the cells in a culture are killed. D) The pattern varies depending on the antimicrobial agent. E) The pattern varies depending on the species.

ethylene oxide

Which of the following chemical agents is used for sterilization? A) alcohol B) phenolics C) ethylene oxide D) chlorine E) soap

gamma radiation

Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper? A) autoclave B) gamma radiation C) microwaves D) sunlight E) ultraviolet radiation

bisphenols

Which of the following disinfectants acts by disrupting the plasma membrane? A) soaps B) aldehydes C) bisphenols D) halogens E) heavy metals

pasteurization

Which of the following does NOT achieve sterilization? A) dry heat B) pasteurization C) autoclave D) supercritical fluids E) ethylene oxide

it cannot be used with heat-liable materials

Which of the following is a limitation of the autoclave? A) It requires an excessively long time to achieve sterilization. B) It cannot inactivate viruses. C) It cannot kill endospores. D) It cannot be used with heat-labile materials. E) It cannot be used with glassware.

membrane filtration

Which of the following is the best method to sterilize heat-labile solutions? A) dry heat B) autoclave C) membrane filtration D) pasteurization E) freezing

freezing

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes? A) lyophilization B) nonionizing radiation C) freezing D) ionizing radiation E) pasteurization

alcohols - open wounds

Which of the following pairs is mismatched? A) Ag — wound dressings B) alcohols — open wounds C) CuSO4 — algicide D) H2O2 — open wounds E) organic acids — food preservation

ultraviolet radiation - desiccation

Which of the following pairs is mismatched? A) ionizing radiation — hydroxyl radicals B) ozone — takes electrons from substances C) plasma sterilization — free radicals D) supercritical fluids — CO2 E) ultraviolet radiation — desiccation

bacteriostatic — kills vegetative bacterial cells

Which of the following pairs of terms is mismatched? A) bacteriostatic — kills vegetative bacterial cells B) germicide - kills microbes C) virucide - inactivates viruses D) sterilant — destroys all living microorganisms E) fungicide — kills yeasts and molds

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

Which of the following regarding antimicrobial control agents is FALSE? A) Contaminating organic debris such as blood or sputum will decrease effectiveness. B) Some agents kill by denaturing microbial cell proteins. C) Some agents affect microbial cell membranes by dissolving lipids. D) Some agents are utilized as both an antiseptic and a disinfectant. E) A true antimicrobial control agent is equally effective against both bacteria and viruses

some agents inactivate viruses by attacking cell membrane lipids

Which of the following regarding antimicrobial control agents is FALSE? A) Contaminating organic debris such as blood or sputum decrease effectiveness. B) Some agents kill by denaturing microbial cell proteins. C) Some agents affect microbial cell membranes by dissolving lipids. D) Silver is used for treating antibiotic-resistant bacteria. E) Some agents inactivate viruses by attacking cell membrane lipids

heat, radiation, and some chemicals

Which of the following results in lethal damage to nucleic acids? A) heat B) radiation C) certain chemicals D) heat and radiation E) heat, radiation, and some chemicals

chlorhexidine

Which of the following substances is used for surgical hand scrubs? A) phenol B) chlorine bleach C) chlorhexidine D) soap E) glutaraldehyde

they are equivalent treatments

Which of the following treatments is the most effective for controlling microbial growth? A) 63°C for 30 minutes B) 72°C for 15 seconds C) 140°C for 4 seconds D) They are equivalent treatments. E) None of the answers is correct.

gram-negative bacteria

Which one of the following is most resistant to chemical biocides? A) gram-negative bacteria B) gram-positive bacteria C) mycobacteria D) protozoan cysts E) viruses with lipid envelopes

moist heat

_______ ______ denatures proteins

nonionizing radiation

_______ __________ damages DNA by creating thymine dimers

heat

_______ denatures enzymes

aseptic

__________ surgery techniques prevent the microbial contamination of wounds

the disinfectant might oxidize molecules

a classmate is trying to determine how a disinfectant might kill cells. you observed that when he spilled the disinfectant in your reduced litmus milk, the litmus turned blue again. you suggest to your classmate that a. the disinfectant might inhibit cell wall synthesis b. the disinfectant might oxidize molecules c. the disinfectant might inhibit protein synthesis d. the disinfectant might denature proteins e. he take his work away from yours

asepsis

absence of significant contamination

desiccation

absence of water prevents metabolism

sepsis

bacterial contamination

disinfection

destroying harmful microorganisms

antisepsis

destroying harmful microorganisms from living tissue

.3 um

high efficiency particulate air (HEPA) filters remove microbes less than _____ um

denatures

high pressure _______ proteins

bacteriostasis

inhibiting, not killing, microbes

lethal mutations

ionizing radiation damages DNA by causing _______ _________

microwaves

kill by heat; not especially antimicrobial

commercial sterilization

killing c. botulinum endospores from canned goods

sanitization

lowering microbial counts on eating utensils to safe levels

thermal death point (TDP)

lowest temperature at which all cells in a liquid culture are killed in 10 min

.22 um

membrane filters removes microbes less than ______ um

thermal death time (TDT)

minimal time for all bacteria in a liquid culture to be killed at a particular temperature

decimal reduction time (DRT)

minutes to kill 90% of a population at a given temperature

thermoduric

organisms survive

plasmolysis

osmotic pressure uses salts and sugars to create a hypertonic environment: causes ____________

filtration

passage of substance through a screen like material; used for heat-sensitive materials

pasteurization

reduces spoilage organisms and pathogens

sterilization

removing and destroying all microbial life

autoclave

steam under pressure; 121 C at 15 psi for 15 minutes; kills all organisms and endospores; steam must contact the item's surface

false

t/f Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization

true

t/f autoclaving is the most effective method of moist heat sterilization

false

t/f microorganisms placed in high concentrations of salt and sugars undergo lysis

true

t/f moist heat destroys organisms by denaturing proteins

true

t/f pseudomonas has been found growing in quaternary ammonium compounds (quats).

true

t/f some antimicrobial chemicals are considered to be disinfectants and antiseptics

false

t/f the pH of the medium has no effect on the activity of the disinfectant being applied

true

t/f the thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature

false

t/f ultraviolet (UV) light causes irreversible breaks in DNA strands

ionizing radiation to break DNA directly

the antimicrobial effect of gamma radiation is due to the ability of _____ ______ __ _____ ___ __________

thymine dimers

the antimicrobial effect of ultraviolet radiation is due to the formation of ______ _________

degerming

the mechanical removal of microbes from a limited area

biocide (germicide)

treatment that kills microbes

140 C for 4 sec

ultra-high-temperature (UHT)

autoclaving

which of the following cannot be used to sterilize a heat-liable solution stored in a plastic container? a. gamma radiation b. ethylene oxide c. supercritical fluids d. autoclaving e. short-wavelength radiation

pasteurization

which of the following does not kill endospores? a. autoclaving b. incineration c. hot air sterilization d. pasteurization e. all of the above kill endospores

ethylene oxide

which of the following is most effective for sterilizing mattresses and plastic petri dishes? a. chlorine b. ethylene oxide c. glutaraldehyde d. autoclaving e. non ionizing radiation

ionizing radiation

which of the following is most likely to be bactericidal? a. membrane filtration b. ionizing radiation c. lyophilization d. deep-freezing e. all of the above

sporicidal

which of the following is not a characteristic of quaternary ammonium compounds? a. bactericidal against gram-postivie bacteria b. sporicidal c. amoebicidal d. fungicidal e. kills enveloped viruses

organic acids

which of the following is used to control microbial growth in food? a. organic acids b. alcohols c. aldehydes d. heavy metals e. all of the above

halogens

which of these disinfectants does not act by disrupting the plasma membrane? a. phenolics b. phenol c. quats d. halogens e. biguanides

ionizing radiation

x rays, gamma rays, electron beams; ionizes water to create reactive hydroxyl radicals; damages DNA by causing lethal mutations