MCB 100 EXAM 4 - ICLICKER QUESTIONS
When microbial control methods are used, microbes are destroyed at a constant rate;
there is no instantaneous death of all the microbes present. This microbial death rate is
influenced by all of the following factors, except
A. the microbial physiological characteristics.
B. the number of microbes that are present.
C. the length of time of exposure to the treatment.
D. the stability of the proteins in the bacteria.
E. the toxins and metabolites produced by the bacteria - Answers -the toxins and
metabolites produced by the bacteria
Determine which of the following statements is true or false and then select the correct
answer sequence: - The term antimicrobial agent includes antibiotics, fungicidal and
antiparasitic agents.
- Bacteriostatic agents inhibit bacterial growth, but do not necessarily kill the organisms
against which they are directed.
- Agents that inhibit bacterial cell wall biosynthesis can be bactericidal.
- Antiseptics are sufficiently nontoxic that they can be applied to skin.
A. false, true, true, true
B. true, true, true, false
C. true, true, false, true
D.false, false, false, false
E. true, true, true, true - Answers -true, true, true, true
Moist heat kills microbes faster than dry heat because _____
A. water has a higher heat capacity than air, which means it takes more energy to raise
the temperature of water.
B. hot water makes the cells swell and burst, while hot air just shrinks the cells.
C. hot air removes the water from the cells but does not kill them right away.
D. hot air causes the cells to release water which evaporates and cools them off and
keeps them alive longer.
E. moist heat kills microbes by denaturing protein and nucleic acid structures and
disrupting cell membranes, which takes less time to kill cells than removing water by dry
heat and killing cells through oxidation reactions. - Answers -moist heat kills microbes
by denaturing protein and nucleic acid structures and disrupting cell membranes, which
takes less time to kill cells than removing water by dry heat and killing cells through
oxidation reactions.
Which of the following statements about pasteurization is not true?
A. Pasteurization reduces the microbial load in heat-sensitive liquids.
B. Pasteurization controls microbes that cause spoilage, such as E. coli and
Salmonella.
C. Pasteurization increases the shelf life of perishable liquids.
D. Pasteurization involves flash heating to 135°C for about a minute.
,E. Pasteurization is a method of sterilization that kills microbes present in food. -
Answers -Pasteurization is a method of sterilization that kills microbes present in food.
An autoclave is able to achieve temperatures higher than that of boiling water
____________
A. by decreasing the volume of liquid.
B. by increasing the temperature higher than boiling water.
C. by increasing the time of exposure to boiling water.
D.Actually, autoclaves cannot reach temperatures higher than boiling water.
E. by increasing the pressure. - Answers -by increasing the pressure
_______ is the appropriate laboratory practices for conducting research with exotic
microbes that are highly infectious and pose significant risk to laboratory personnel, but
for which there are available treatments.
A. BSL1
B. BSL2
C. BSL3
D. BSL4
E. BSL5 - Answers -BSL3
A particular sterilization process takes 60 minutes to kill all organisms in a sample with
106 microbes. How long does it take to eliminate 99% (2 D-values) of the organisms
using this process?
A. 10 minutes
B. 20 minutes
C. 30 minutes
D. 40 minutes
E. 50 minutes - Answers -20 minutes
Consider each of the following statements and determine whether they are true or false,
then select the correct series of responses: - Moist-heat sterilization methods require
application of higher temperatures for longer periods of time than dry-heat sterilization
methods. - Pasteurization is a method of sterilization that kills microbes present in food.
- The goal of tyndallization is to rid canned produce of Clostridium botulinum
endospores.
A. true, false, false
B. false, false, true
C. false, true, true
D. false, false, false
E. true, true, true - Answers -false, false, true
In an autoclave, the application of ______ to _______ is increased to allow the _______
to achieve temperatures above the boiling point of water.
A. pressure | steam | agar
B. heat | pressure | agar
C. pressure | steam | steam
, D. heat | medium | steam
E. heat | water | medium - Answers -pressure | steam | steam
Oxidizing agents such as chlorine or hydrogen peroxide are particularly effective against
_________ organisms.
A. microaerophilic
B. aerobic
C. facultative aerobic
D.thermotolerant
E. anaerobic - Answers -anaerobic
Which of the following is used to sterilize items that should not, or cannot, be exposed
to heat or water?
A. formaldehyde
B. hydrogen peroxide
C. calcium hypochlorite
D. triclosan
E. ethylene oxide - Answers -ethylene oxide
Seventy percent alcohol and quaternary ammonium compounds are effective against
A. non-enveloped viruses.
B. non-enveloped and enveloped viruses.
C. bacterial endospores.
D. protozoan cysts.
E. enveloped viruses.
F. bacterial endospores and protozoan cysts, but not prions.
G. bacterial endospores and prions.
H. prions - Answers -enveloped viruses
Which of the following antimicrobial agents is the most toxic to humans?
A. 70% alcohol
B. quaternary ammonium compounds
C. chloramines
D. iodine
E. ethylene oxide - Answers -ethylene oxide
Contaminated hospital equipment represents a difficult environment to control against
harmful microbial growth. Which of the following statements regarding influences that
affect disinfection of hospital equipment is an accurate statement?
A. The presence of organic matter, such as dried blood or protein, will not affect the
action of antimicrobial agents.
B. Biofilms, often found contaminating hospital equipment, are relatively simple targets
for microbicides to reach effectively.
C. Antimicrobial agents work best under reduced temperatures and pressures.
D.Halogens (such as chlorine) are surface-active agents that act by decreasing the
surface tension so that microbes are more easily removed.
When microbial control methods are used, microbes are destroyed at a constant rate;
there is no instantaneous death of all the microbes present. This microbial death rate is
influenced by all of the following factors, except
A. the microbial physiological characteristics.
B. the number of microbes that are present.
C. the length of time of exposure to the treatment.
D. the stability of the proteins in the bacteria.
E. the toxins and metabolites produced by the bacteria - Answers -the toxins and
metabolites produced by the bacteria
Determine which of the following statements is true or false and then select the correct
answer sequence: - The term antimicrobial agent includes antibiotics, fungicidal and
antiparasitic agents.
- Bacteriostatic agents inhibit bacterial growth, but do not necessarily kill the organisms
against which they are directed.
- Agents that inhibit bacterial cell wall biosynthesis can be bactericidal.
- Antiseptics are sufficiently nontoxic that they can be applied to skin.
A. false, true, true, true
B. true, true, true, false
C. true, true, false, true
D.false, false, false, false
E. true, true, true, true - Answers -true, true, true, true
Moist heat kills microbes faster than dry heat because _____
A. water has a higher heat capacity than air, which means it takes more energy to raise
the temperature of water.
B. hot water makes the cells swell and burst, while hot air just shrinks the cells.
C. hot air removes the water from the cells but does not kill them right away.
D. hot air causes the cells to release water which evaporates and cools them off and
keeps them alive longer.
E. moist heat kills microbes by denaturing protein and nucleic acid structures and
disrupting cell membranes, which takes less time to kill cells than removing water by dry
heat and killing cells through oxidation reactions. - Answers -moist heat kills microbes
by denaturing protein and nucleic acid structures and disrupting cell membranes, which
takes less time to kill cells than removing water by dry heat and killing cells through
oxidation reactions.
Which of the following statements about pasteurization is not true?
A. Pasteurization reduces the microbial load in heat-sensitive liquids.
B. Pasteurization controls microbes that cause spoilage, such as E. coli and
Salmonella.
C. Pasteurization increases the shelf life of perishable liquids.
D. Pasteurization involves flash heating to 135°C for about a minute.
,E. Pasteurization is a method of sterilization that kills microbes present in food. -
Answers -Pasteurization is a method of sterilization that kills microbes present in food.
An autoclave is able to achieve temperatures higher than that of boiling water
____________
A. by decreasing the volume of liquid.
B. by increasing the temperature higher than boiling water.
C. by increasing the time of exposure to boiling water.
D.Actually, autoclaves cannot reach temperatures higher than boiling water.
E. by increasing the pressure. - Answers -by increasing the pressure
_______ is the appropriate laboratory practices for conducting research with exotic
microbes that are highly infectious and pose significant risk to laboratory personnel, but
for which there are available treatments.
A. BSL1
B. BSL2
C. BSL3
D. BSL4
E. BSL5 - Answers -BSL3
A particular sterilization process takes 60 minutes to kill all organisms in a sample with
106 microbes. How long does it take to eliminate 99% (2 D-values) of the organisms
using this process?
A. 10 minutes
B. 20 minutes
C. 30 minutes
D. 40 minutes
E. 50 minutes - Answers -20 minutes
Consider each of the following statements and determine whether they are true or false,
then select the correct series of responses: - Moist-heat sterilization methods require
application of higher temperatures for longer periods of time than dry-heat sterilization
methods. - Pasteurization is a method of sterilization that kills microbes present in food.
- The goal of tyndallization is to rid canned produce of Clostridium botulinum
endospores.
A. true, false, false
B. false, false, true
C. false, true, true
D. false, false, false
E. true, true, true - Answers -false, false, true
In an autoclave, the application of ______ to _______ is increased to allow the _______
to achieve temperatures above the boiling point of water.
A. pressure | steam | agar
B. heat | pressure | agar
C. pressure | steam | steam
, D. heat | medium | steam
E. heat | water | medium - Answers -pressure | steam | steam
Oxidizing agents such as chlorine or hydrogen peroxide are particularly effective against
_________ organisms.
A. microaerophilic
B. aerobic
C. facultative aerobic
D.thermotolerant
E. anaerobic - Answers -anaerobic
Which of the following is used to sterilize items that should not, or cannot, be exposed
to heat or water?
A. formaldehyde
B. hydrogen peroxide
C. calcium hypochlorite
D. triclosan
E. ethylene oxide - Answers -ethylene oxide
Seventy percent alcohol and quaternary ammonium compounds are effective against
A. non-enveloped viruses.
B. non-enveloped and enveloped viruses.
C. bacterial endospores.
D. protozoan cysts.
E. enveloped viruses.
F. bacterial endospores and protozoan cysts, but not prions.
G. bacterial endospores and prions.
H. prions - Answers -enveloped viruses
Which of the following antimicrobial agents is the most toxic to humans?
A. 70% alcohol
B. quaternary ammonium compounds
C. chloramines
D. iodine
E. ethylene oxide - Answers -ethylene oxide
Contaminated hospital equipment represents a difficult environment to control against
harmful microbial growth. Which of the following statements regarding influences that
affect disinfection of hospital equipment is an accurate statement?
A. The presence of organic matter, such as dried blood or protein, will not affect the
action of antimicrobial agents.
B. Biofilms, often found contaminating hospital equipment, are relatively simple targets
for microbicides to reach effectively.
C. Antimicrobial agents work best under reduced temperatures and pressures.
D.Halogens (such as chlorine) are surface-active agents that act by decreasing the
surface tension so that microbes are more easily removed.
