Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
Which of the following disinfectants acts by disrupting the plasma membrane?
1)
A)
heavy metals
B)
soaps
C)
bisphenols
D)
halogens
E)
aldehydes
2)
Which of the following substances is used for surgical hand scrubs?
2)
A)
soap
B)
chlorhexidine
C)
chlorine bleach
D)
glutaraldehyde
E)
phenol
3)
Which of the following regarding antimicrobial control agents is FALSE?
3)
A)
Some agents are utilized as both an antiseptic and a disinfectant.
B)
A true antimicrobial control agent is equally effective against both bacteria and viruses.
C)
Contaminating organic debris such as blood or sputum will decrease effectiveness.
D)
Some agents kill by denaturing microbial cell proteins.
E)
Some agents affect microbial cell membranes by dissolving lipids.
Explanation:
4)
Which one of the following is most resistant to chemical biocides?
4)
A)
gram–negative bacteria
B)
viruses with lipid envelopes
C)
protozoan cysts
D)
mycobacteria
E)
gram–positive bacteria
5)
Which of the following methods is used to preserve food by slowing the metabolic processes of
foodborne microbes?
5)
A)
ionizing radiation
B)
nonionizing radiation
C)
lyophilization
D)
pasteurization
E)
freezing
Figure 7.1
A suspension of 106Bacillus cereus endospores was put in a hot–air oven at 170°C. Plate counts were used to
determine the number of endospores surviving at the time intervals shown.
6)
In Figure 7.1, the decimal reduction time (D value) for the culture is approximately
6)
A)
0 minutes.
B)
10 minutes.
C)
30 minutes.
D)
40 minutes.
E)
60 minutes.
7)
Which of the following is a limitation of the autoclave?
7)
A)
It cannot be used with glassware.
B)
It requires an excessively long time to achieve sterilization.
C)
It cannot kill endospores.
D)
It cannot inactivate viruses.
E)
It cannot be used with heat–labile materials.
8)
Which of the following treatments is the most effective for controlling microbial growth?
8)
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.
9)
If you were preparing nutrient agar at home and did not have an autoclave, what could you use to
sterilize the nutrient agar?
9)
A)
boiling for one hour
B)
hydrogen peroxide
C)
pressure cooker at 121°C for 15 minutes
D)
oven at 121°C for one hour
E)
bleach
10)
The preservation of beef jerky from microbial growth relies on which method of microbial control?
10)
A)
ionizing radiation
B)
filtration
C)
lyophilization
D)
desiccation
E)
supercritical CO2
Figure 7.2
Assume 109E. coli cells/ml are in a flask.
11)
Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?
11)
A)
a
B)
b
C)
c
D)
d
E)
e
12)
Which of the following best describes the pattern of microbial death?
12)
A)
All the cells in a culture die at once.
B)
The cells in a population die at a constant rate.
C)
The pattern varies depending on the species.
D)
The pattern varies depending on the antimicrobial agent.
E)
Not all of the cells in a culture are killed.
13)
Disinfection of water is achieved by all of the following EXCEPT
13)
A)
UV radiation.
B)
chlorine.
C)
peracetic acid.
D)
copper sulfate.
E)
ozone.
14)
Application of heat to living cells can result in all of the following EXCEPT
14)
A)
alteration of membrane permeability.
B)
breaking of hydrogen bonds.
C)
denaturation of enzymes.
D)
damage to nucleic acids.
E)
decreased thermal death time.
15)
All of the following substances are used to preserve foods EXCEPT
15)
A)
potassium sorbate.
B)
biguanides.
C)
sodium nitrite.
D)
calcium propionate.
E)
nisin.
16)
All of the following factors contribute to hospital–acquired infections EXCEPT
16)
A)
some bacteria metabolize disinfectants.
B)
bacteria may be present in commercial products such as mouthwash.
C)
invasive procedures can provide a portal of entry for bacteria.
D)
gram–negative bacteria are often resistant to disinfectants.
E)
None of the answers is correct; all of these factors may contribute to hospital–acquired
infection.
17)
Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?
17)
A)
ultraviolet radiation
B)
microwaves
C)
sunlight
D)
gamma radiation
E)
autoclave
18)
Oxidizing agents include all of the following EXCEPT
18)
A)
ozone.
B)
hydrogen peroxide.
C)
chlorine.
D)
glutaraldehyde.
E)
iodine.
19)
Which of the following results in lethal damage to nucleic acids?
19)
A)
heat
B)
radiation
C)
certain chemicals
D)
heat and radiation
E)
heat, radiation, and some chemicals
E
Table 7.1
A disk–diffusion test using Staphylococcus gave the following results:
Disinfectant Zone of inhibition (mm)
A 0
B2.5
C10
D 5
20)
In Table 7.1, which compound was the most effective against E. coli?
20)
A)
A
B)
B
C)
C
D)
D
E)
The answer cannot be determined based on the information provided.
E
D
Figure 7.1
A suspension of 106Bacillus cereus endospores was put in a hot–air oven at 170°C. Plate counts were used to
determine the number of endospores surviving at the time intervals shown.
21)
In Figure 7.1, what is the thermal death time?
21)
A)
120 minutes
B)
100°C
C)
60 minutes
D)
150°C
E)
The answer cannot be determined based on the information provided.
22)
Which of the following chemical agents is used for sterilization?
22)
A)
alcohol
B)
phenolics
C)
soap
D)
chlorine
E)
ethylene oxide
E
C
Figure 7.2
Assume 109E. coli cells/ml are in a flask.
23)
Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15
minutes at time x?
23)
A)
a
B)
b
C)
c
D)
d
E)
e
Figure 7.1
A suspension of 106Bacillus cereus endospores was put in a hot–air oven at 170°C. Plate counts were used to
determine the number of endospores surviving at the time intervals shown.
24)
In Figure 7.1, the thermal death point for this culture is
24)
A)
15 minutes.
B)
50°C.
C)
170°C.
D)
30 minutes.
E)
The answer cannot be determined based on the information provided
25)
All of the following substances are effective against nonenveloped viruses EXCEPT
25)
A)
chlorine.
B)
ethylene oxide.
C)
ozone.
D)
alcohol.
E)
None of the answers is correct; all of these are equally effective against nonenveloped viruses.
26)
Which of the following pairs is mismatched?
26)
A)
alcohols — open wounds
B)
H2O2 — open wounds
C)
CuSO4 — algicide
D)
organic acids — food preservation
E)
Ag — wound dressings
27)
Which of the following does NOT achieve sterilization?
27)
A)
supercritical fluids
B)
dry heat
C)
ethylene oxide
D)
pasteurization
E)
autoclave
28)
Ethylene oxide
28)
A)
requires high heat to be effective.
B)
is the active chemical in household bleach.
C)
is a sterilizing agent.
D)
is a good antiseptic.
E)
is not sporicidal.
29)
Which of the following regarding antimicrobial control agents is FALSE?
29)
A)
Contaminating organic debris such as blood or sputum decrease effectiveness.
B)
Some agents inactivate viruses by attacking cell membrane lipids.
C)
Some agents affect microbial cell membranes by dissolving lipids.
D)
Some agents kill by denaturing microbial cell proteins.
E)
Silver is used for treating antibiotic–resistant bacteria.
Table 7.3
The following data were obtained by incubating gram–positive bacteria in
nutrient medium + disinfectant for 24 hr, then transferring one loopful to
nutrient medium (subculturing). (+ = growth; – = no growth)
30)
In Table 7.3, which disinfectant is the most effective at stopping bacterial growth?
30)
A)
Doom
B)
K.O.
C)
Mortum
D)
Sterl
E)
The answer cannot be determined based on the information provided.
31)
An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n)
31)
A)
virucide.
B)
disinfectant.
C)
fungicide.
D)
antiseptic.
E)
aseptic.