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Microbiology, 5/e

Lansing M Prescott, Augustana College
Donald A Klein, Colorado State University
John P Harley, Eastern Kentucky University

Control of Microorganisms by Physical and Chemical Agents

Multiple Choice Quiz

Choose the best answer


1	Preserve foods by using salts and sugars works by
		A)	raising pH.
		B)	depleting nutrients.
		C)	lowering osmotic pressure.
		D)	creating a hypertonic environment.
		E)	creating a hypotonic environment.


2	Which of the following methods will not sterilize?
		A)	500 mg/L ethylene oxide at 50¹/₄ C for 4 hours
		B)	aqueous glutaraldehyde for 10 hours
		C)	dry heat at 171¹/₄ C for 1 to 2 hours
		D)	121¹/₄ C at 15 lb/in pressure for 15 to 20 minutes
		E)	100¹/₄ C boiling water for 30 minutes


3	Which of the following does not kill endospores?
		A)	Autoclave
		B)	Incineration
		C)	Hot air sterilization
		D)	Pasteurization
		E)	All of these processes kill endospores.


4	Which of the following is best to sterilize heat labile solutions?
		A)	Dry heat
		B)	Autoclave
		C)	Membrane filtration
		D)	Pasteurization
		E)	None of these processes is useful for sterilizing heat labile solutions.


5	Which of the following is bactericidal?
		A)	Membrane filtration
		B)	Ionizing radiation
		C)	Freeze-drying
		D)	Deep freezing
		E)	All of these processes kill bacteria.


6	Which of the following substances can sterilize?
		A)	Alcohol
		B)	Cetylpyridinium chloride
		C)	Ethylene oxide
		D)	Chlorine
		E)	Silver nitrate


7	Which of the following is not a disinfectant containing a heavy metal?
		A)	Silver nitrate
		B)	Mercurochrome
		C)	Merthiolate
		D)	Copper sulfate
		E)	Chlorine


8	Which of the following is most effective for sterilizing mattresses and plastic Petri plates?
		A)	Chlorine
		B)	Ethylene oxide
		C)	Glutaraldehyde
		D)	Autoclave
		E)	Ultraviolet radiation

Use this information to answer the following question(s).

Phenol Coefficient
Compound	*Salmonella typhi*	*Staphylococcus aureus*
Phenol	1	1
Cetylpyridinium chloride	228	337
Hexachlorophene	5-15	15-40
Merthiolate	600	62.5
Ethanol	0.04	0.04


9	Which disinfectant was the most effective against Salmonella?
		A)	Phenol
		B)	Cetylpyridinium chloride
		C)	Hexachlorophene
		D)	Merthiolate
		E)	Can't tell


10	Which disinfectant would be most effective against Bacillus cereus?
		A)	Phenol
		B)	Cetylpyridinium chloride
		C)	Hexachlorophene
		D)	Merthiolate
		E)	Can't tell


11	Which disinfectant would be most effective against Staphylococcus found in a blood spill?
		A)	Phenol
		B)	Cetylpyridinium chloride
		C)	Hexachlorophene
		D)	Merthiolate
		E)	Can't tell


12	If a canning procedure is not properly followed, which type of microbe is most likely to grow in the canned food?
		A)	Obligate Aerobe
		B)	Acidophile
		C)	Microaerophile
		D)	Mesophile
		E)	Obligate Anaerobe


13	Sweet and salty foods frequently don't require refrigeration to prevent spoilage because they have
		A)	insufficient nutrients.
		B)	low pH.
		C)	high concentration of solutes.
		D)	toxic alkaline chemicals.
		E)	naturally occurring antibiotics.


14	If a 1:600 dilution of a test compound kills a standard population of Staphylococcus aureus in 10 minutes but not 5 minutes while a 1:60 dilution of phenol kills the population in the same time, what is the phenol coefficient of the test compound?
		A)	1
		B)	5
		C)	10
		D)	50
		E)	100


15	The lowest temperature that kills all microorganisms in a liquid suspension in 10 minutes is known as the
		A)	decimal reduction time.
		B)	thermal death point.
		C)	thermal death temperature.
		D)	thermal death time.
		E)	D value.


16	The time required to kill 90% of the microorganisms in a sample at a specific temperature is the
		A)	decimal reduction time.
		B)	thermal death point.
		C)	thermal death temperature.
		D)	F value.
		E)	D value.


17	The time in minutes at a specific temperature needed to kill a population of cells is the
		A)	decimal reduction time.
		B)	thermal death point.
		C)	thermal death temperature.
		D)	F value.
		E)	D value.


18	Which of the following is a limitation of the autoclave?
		A)	It takes too long to sterilize.
		B)	It lacks the ability to inactivate viruses.
		C)	It lacks the ability to kill endospores.
		D)	It will destroy heat labile materials.
		E)	It cannot be used with glassware.


19	A(n) ____ is used to prevent infection by killing or inhibiting pathogen growth on animal tissues.
		A)	bacteriostatic agent
		B)	sterilant
		C)	sanitizer
		D)	disinfectant
		E)	antiseptic


20	If 90% of the population of bacteria that had 106 CFU/ml are killed there will be ____ remaining CFU/ml.
		A)	107
		B)	9 x 10⁵
		C)	105
		D)	10
		E)	no


21	Which of the following items could be sterilized by dry heat sterilization?
		A)	Intravenous (IV) solution
		B)	Plastic IV bags
		C)	Glass pipets
		D)	rubber gloves
		E)	plastic petri dishes


22	Which of the following is best used for long term storage of microbial samples when carried out properly?
		A)	storage in a freezer at -10¹/₄ C
		B)	storage in a freezer at ultra low temperatures (- 70¹/₄ C)
		C)	storage in a refrigerator on an agar slant
		D)	storage on a petri plate at room temperature
		E)	it is not possible to routinely store viable microbial samples


23	Which of the following disinfectants acts by disrupting microbial membranes?
		A)	Cationic detergents
		B)	Halogens
		C)	Heavy metals
		D)	Aldehydes
		E)	Sterilizing gases


24	Which of the following was the first widely used antiseptic and disinfectant?
		A)	Chlorine
		B)	Phenol
		C)	Iodine
		D)	Alcohol
		E)	Merthiolate

Compare the following entities (I and II).


25	I.the percentage of cells killed by a procedure with a D₁₀₀ value of 8 minutes II.the percentage of cells killed by a procedure with a D₁₀₀ value of 5 minutes
		A)	I is greater than II, mark A
		B)	I is less than II, mark B
		C)	I is exactly or approximately equal to II, mark C
		D)	I may stand in more than one of the above relations to II, mark D


26	I.ability of boiling a solution for 15 minutes to sterilize the solution II.ability of membrane filtration a solution for 15 minutes to sterilize the same solution
		A)	I is greater than II, mark A
		B)	I is less than II, mark B
		C)	I is exactly or approximately equal to II, mark C
		D)	I may stand in more than one of the above relations to II, mark D


27	I.time required to autoclave a liter of culture media that has been dispensed 5 ml/tube II.time required to autoclave a liter of culture media that is in a 2-liter flask
		A)	I is greater than II, mark A
		B)	I is less than II, mark B
		C)	I is exactly or approximately equal to II, mark C
		D)	I may stand in more than one of the above relations to II, mark D


28	I.ability of membrane filtration to sterilize a heat labile culture medium II.ability of autoclaving to sterilize a the same heat labile culture medium
		A)	I is greater than II, mark A
		B)	I is less than II, mark B
		C)	I is exactly or approximately equal to II, mark C
		D)	I may stand in more than one of the above relations to II, mark D


29	Who is credited with developing a procedure to heat wine at temperatures well below boiling to prevent spoilage of the wine?
		A)	Lister
		B)	Gram
		C)	Koch
		D)	Pasteur
		E)	Watkins


30	All of the following are sporicidal except
		A)	glutaraldehyde
		B)	ethylene oxide
		C)	formaldehyde
		D)	alcohol
		E)	stabilized hydrogen peroxide

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