Define niche
A. ecological environment
B. by-product of microbial metabolic
activities
C. microbial growth
D. host-parasite
relationship
E. None of the above
A. ecological environment
Microbes may attempt to adjust the environment (temperature, pH,
etc.) to their optimal requirements in
order to compete for nutrients.
A. True
B. False
A. True
The pathogenesis of disease can involve digestion of tissues by
extracellular enzymes or physical
blocking of capillaries due to
unlimited microbial growth.
A. True
B. False
A. True
The study of microbial metabolism is essential to a complete
understanding of the host-parasite
relationship.
A. True
B. False
A. True
Microorganisms, as other forms of life, may alter their environment
to a certain extent and use chemical
compounds in solutions as
sources of energy or components for growth and reproduction.
A.
True
B. False
A. True
All cellular activities are mediated by:
A. Enzymes
B.
Carbohydrates
C. Lipids
D. All of the above
E. None of
the above
A. Enzymes
7. In order to observe microbial enzymatic activity, various kinds of
specifically prepared media are
inoculated with pure cultures of
microorganisms.
A. True
B. False
A. True
8. Microbes multiply during the refrigeration period and exhibit
their respective enzymatic activities.
A. True
B. False
B. False
Many distinctive enzyme activities can be demonstrated by testing for
the by-products resulting from the
action of enzymes on specific
substances within the special media.
A. True
B. False
A. True
10. Microbial species can differ greatly and may be identified by the
actions of their enzymes.
A. True
B. False
A. True
11. By using a series of different media or biochemical tests, a
pattern of activity can be established for a
species. Such
reaction patterns can be used in the identification and the
differentiation of
microorganisms.
A. True
B. False
A. True
12. Microbial reaction patterns to the following media can be used in
the identification and the
differentiation of
microorganisms.
A. Starch agar
B. Nutrient gelatin
C.
Urea broth
D. Hydrogen peroxide
E. All of the above
E. All of the above
13. Gram stains alone can be used to identify microorganisms.
A.
True
B. False
B. False
14. ________are the prime source of energy and carbon for the
synthesis of cellular components.
A. Enzymes
B.
Carbohydrates
C. Lipids
D. Simple sugars
E. None of the above
B. Carbohydrates
15. _______ such as glucose and galactose are important in both human
and microbial metabolism.
A. Enzymes
B.
Carbohydrates
C. Lipids
D. Simple sugars
E. None of the above
D. Simple sugars
16. In the case of microorganisms, most of the carbohydrates
available to them are ________ that are made
up of many ________
units.
A. Polysaccharide, monosaccharide
B. Monoaccharide,
monosacccharide
C. Monosaccharide, polysacccharide
D.
Disaccharide, trisacccharide
E. None of the above
A. Polysaccharide, monosaccharide
17. Cellulose and starch are two common examples of polysaccharides
that are made up of many
monosacccharide units.
A.
True
B. False
A. True
18. Cellulose and starch are polymers of glucose.
A.
True
B. False
A. True
19. The basic difference between cellulose and starch is the
structural arrangement of the glucose units,
which leads to the
chemical difference.
A. True
B. False
A. True
20. The enzyme responsible for the hydrolysis of starch is called
amylase.
A. True
B. False
A. True
21. Amylase is an extracellular enzyme
A. True
B. False
A. True
22. Amylase is secreted through the cell membrane to degrade complex
substances (starch) into smaller
units (maltose), which can
readily enter the cell.
A. True
B. False
A. True
23. Amylase acts on starch to yield maltose (a disaccharide composed
of two glucose molecules), which is
then further digested by
cells.
A. True
B. False
A. True
24. To inoculate a starch agar plate for the amylase test place a
straight line of inoculum from a pure
bacterial culture down the
center of your starch plate.
A. True
B. False
A. True
To inoculate a starch agar plate for the amylase test perform the
streak plate technique of inoculation.
A. True
B. False
B. False
After 24-48 hours of incubation at 37°C the amylase results can
immediately be determined visually.
A. True
B. False
B. False
You must carefully flood the starch agar plate with gram’s iodine
solution to analyze the amylase test
results.
A.
True
B. False
A. True
A positive reaction to the amylase test will be a zone of inhibition
around the microbial growth
A. True
B. False
B. False
A clear zone around the microbial growth is an indication that starch
has been hydrolyzed by bacterial
amylase.
A. True
B. False
A. True
Iodine will stain starch a _____color.
A. Blue
B.
Bluish-purple
C. Purple
D. Red
E. None of the above
B. Bluish-purple
Where amylase has digested the starch, there will be a colorless zone
indicating that the starch was
hydrolyzed.
A. True
B. False
A. True
In a ______amylase test reaction, the whole plate, including the area
around the organism, remains a
bluish-purple color, indicating
that the organism did not have the enzyme amylase.
A.
Negative
B. False-negative
C. Positive
D.
False-Positive
E. A and B all answers with the word negative are correct
E. A and B all answers with the word negative are correct
Protein hydrolysis can be detected using a gelatin slant agar tube
(Awaiting confirmation from Prof.)
A. True
B. False
B. False
When in solution, gelatin agar liquefies at warm temperatures of
about 15°C.
A. True
B. False
B. False
At room temperature or below, gelatin agar becomes liquid.
A.
True
B. False
B. False
When bacteria that produce the enzyme gelatinase are grown in a
gelatin medium, the enzyme
hydrolyzes the gelatin molecule and
the medium cannot solidify, even at cold temperature.
A.
True
B. False
A. True
Gelatinase is a:
A. Protease
B. DNAse
C.
Endonuclease
D. All of the above
E. None of the above
A. Protease
Inoculate the gelatin deep with a pure culture, using a stab with an
inoculation needle and incubate at:
A. 4°C for 48 hours
B.
25°C for 48 hours
C. 30°C for 48 hours
D. 37°C for 48
hours
E. None of the above
D. 37°C for 48 hours
A gelatin deep agar tube will be liquid at:
A. 4°C for 48
hours
B. 25°C for 48 hours
C. 37°C for 48 hours
D. All
of the above
E. None of the above
C. 37°C for 48 hours
To ensure gelatin hydrolysis after incubation for 24-48 hours, place
tubes at 4°C for 30 min. and
examine the tubes for:
A.
Liquefaction
B. Polymerization
C. Putrefaction
D. Color
change
E. pH change
A. Liquefaction
To ensure gelatin hydrolysis after incubation for 24-48 hours, place
tubes at 4°C for 30 min. and if all
tubes are solidified, replace
them in the incubator for further growth and re-examine them
every:
A. 6 hours for 2 days
B. 12 hours for 3 days
C.
24 hours for 3 days
D. 24 hours for 2 days
E. All of the above
C. 24 hours for 3 days
A positive gelatinase result is indicated by liquefied agar in a tube
that remains liquid even after being
placed in the
refrigerator.
A. True
B. False
A. True
_____ is an intestinal microbe with the ability to produce
urease.
A. Proteus
B. M. luteus
C. S.
marscesans
D. C. albicans
E. S. cerevesiae
A. Proteus
The urease enzyme splits ____ from the ____ molecule
A. Ammonia,
water
B. Ammonia, oxygen
C. Ammonia, carbon
D. Ammonia,
urea
E. All of the above
D. Ammonia, urea
Most enteric pathogens do not produce urease.
A. True
B. False
A. True
____is a common cause of urinary tract infections.
A.
Proteus
B. Escherichia coli
C. Clostridium difficile
D.
A and B
E. B and C
D. A and B
Urea broth is a buffered solution of ____extract and urea.
A.
Soy
B. Blood
C. Yeast
D. Carageenan
E. C and D
C. Yeast
Urea broth contains phenol red as a ___indicator.
A.
Temperature
B. pH
C. Nutrients
D. Isoelectric
point
E. None of the above
B. pH
Since urea is unstable and breaks down in the autoclave steam
pressure, the media is sterilized by ____
A. Heat
B.
Formalin
C. Filtration
D. Glutaraldehyde
E. None of the above
C. Filtration
When urease is produced by an organism in urea broth, the ammonium
that is released
A. raises the pH
B. decreases the
pH
C. maintains the pH
D. neutralizes the pH
E. None of
the above
A. raises the pH
When the pH increases, ______changes from a yellow-orange color (pH
6.8) to a pink color (pH 8.1 or
more).
A. trypan
blue
B. trypsin
C. phenol red
D. phenol orange
E.
phenol yellow
C. phenol red
If urea broth turns a hot pink color within ____ hours post
inoculation, this indicates the presence of the
enzyme
urease.
A. 72
B. 24
C. 4
D. 8
E. 48
B. 24
Catalase is a/an_____ that catalyzes the breakdown of hydrogen
peroxide (H2O2) to water and oxygen.
A. extracellular
enzyme
B. endotoxin
C. secreted enzyme
D. intracellular
enzyme
E. None of the above
D. intracellular enzyme
The catalase test is useful for a quick separation of
catalase-positive Staphylococci from catalase-
negative
Streptococci and Enterococci.
A. True
B. False
A. True
The presence of _____can be detected by adding a drop of 5% H2O2 to a
colony and observing for the
production of bubbles of O2. This
test can also be performed in a drop of H2O2 on a slide.
A.
Casease
B. Amylase
C. Collagenase
D. Catalase
E.
Superoxide dismutase
D. Catalase
Blood cells contain catalase.
A. True
B. False
A. True
Coagulase is an enzyme, produced by____, which coagulates blood
plasma. Coagulase helps the
organism evade the host immune system
by isolating itself from antibodies or cells that might attempt
to
phagocytize the bacteria.
A. Micrococcus luteus
B.
S. pneumoniae
C. S. epidermidis
D. S. aureus
E. None of
the above
D. S. aureus
Coagulase is not produced by S. epidermidis or by any other
gram-positive coccus. (Awaiting
confirmation from Prof.)
A.
True
B. False
A. True
The coagulase test is done in _____and the sample is incubated at
37°C for 24 hours. A tube that
solidifies (clots) shows the
presence of coagulase. This reaction can occur as fast as 4
hours.
A. sheep plasma
B. rabbit plasma
C. mouse
plasma
D. human plasma
E. None of the above
B. rabbit plasma
How does the starch agar test demonstrate that amylase is an
exoenzyme?
A. Starch in the agar is hydrolyzed in the presence of
amylase
B. Starch in the microbe is hydrolyzed in the presence of
amylase
C. Lipids in the agar are hydrolyzed in the presence of
amylase
D. Casein in the agar is hydrolyzed in the presence of amylase
A. Starch in the agar is hydrolyzed in the presence of amylase
What is the benefit to a microbe in producing a protease such as
gelatinase?
A. Hydrolyze protein
B. Hydrolyze lipid
C.
Hydrolyze starch
D. Enable microbial penetration deeper into the
body
E. A and D
E. A and D
Why is the breakdown of peroxide useful to a bacterium?
A.
Neutralize toxins
B. Neutralize free radicals
C. Neutralize
reactive oxygen species
D. Peroxide is used in microbial
metabolism
E. B and C
E. B and C
Bacterial identification is based on:
A. Morphology
B.
Arrangement
C. Staining characteristics
D. Biochemical
differences and genetic analysis
E. All of the above
E. All of the above
Indole production from tryptophan differentiates _____ from other
gastrointestinal bacteria.
A. Proteus
B. Escherichia
coli
C. Clostridium difficile
D. A and B
E. B and C
B. Escherichia coli
If a red color is produced after incubation in SIM medium and after
the addition of Erhlich’s reagent, the
bacterium hydrolyzes
_____to indole.
A. H2S
B. Valine
C.
Phenylalanine
D. Threonine
E. Tryptophan
E. Tryptophan
What does Erhlich’s reagent do?
A. Detects motility
B.
Detects H2S
C. Detects tryptophan
D. Detects indole
D. Detects indole
H2S production in SIM medium from sulfur containing amino acids
differentiates Proteus vulgaris,
Shigella and Salmonella from
other gastrointestinal bacteria.
A. True
B. False
A. True
The black color produced when sulfur reacts with iron in the SIM
medium indicates _______
A. Motility
B. H2S
production
C. Tryptophan production
D. Indole
production
E. None of the above
B. H2S production
Define carbohydrate fermentation
A. Production of acid from
sugars
B. Production of acid and gas from sugars
C.
Breakdown of sugars such as glucose and lactose
D. All of the
above
E. None of the above
D. All of the above
Define coliforms:
A. rod-shaped
B. Gram-negative
C.
non-spore forming
D. motile or non-motile
E. All of the above
E. All of the above
______production is seen as the formation of bubbles in the inverted
Durham fermentation tube, and
ammonia production by a change in
color from red to fuchsia.
A. H2O2
B. Gas
C.
Nitrogen
D. Catalase
E. None of the above
B. Gas
Escherichia coli produces alkaline by products and gas from
lactose.
A. True
B. False
B. False
Motility assay: if SIM agar is inoculated properly, motile bacteria
will move away from the line of
inoculation and give a
_____appearance.
A. Slimy
B. Undulating
C.
Swimming
D. Fuzzy
E. Sharp
D. Fuzzy
Many Gram-negative bacteria can be distinguished by the metabolic
pathway they utilize to
ferment fructose.
A. True
B. False
B. False
MR-VP broth is used to test for the pathway used to ferment
fructose.
A. True
B. False
B. False
MR-VP broth contains fructose as the only fermentable carbohydrate;
peptone; and a phosphate buffer.
A. True
B. False
B. False
MR-VP broth is used to test for two glucose fermentation pathways:
the “mixed acid” fermentation
(detected by the Methyl Red Test)
and the “butanediol” fermentation (detected by the
Voges-Proskauer
Test).
A. True
B. False
A. True
Some organisms, typified by E. coli, carry out a “mixed acid”
fermentation, named for the large amounts
of organic acids that
are produced as end-products during the fermentation of glucose, gases
may also be
produced.
A. True
B. False
A. True
The large amount of ______that are produced during the fermentation
of glucose overcome the
buffering system in the MR-VP broth and
lower the pH of the medium to about 4.0.
A. organic acids
B.
mixed acids
C. butanediol
D. A and B
E. All of the above
D. A and B
The test uses methyl red, a pH indicator that has a red color at a pH
lower than 4.5 and a yellow color
when the pH is above
6.0.
A. 4.5, 6.0
B. 4.5, 5.0
C. 4.5, 7.0
D. 4.5,
8.0
E. None of the above
A. 4.5, 6.0
A positive Methyl-Red test, which is indicative of the lowered pH of
________, will produce a light-red
(pinkish) color when methyl
red is added to the MR-VP broth (after incubation).
A. Ethanol
production
B. carbon dioxide synthesis
C. formation of
hydrogen gases
D. mixed acid fermentation
E. None of the above
D. mixed acid fermentation
The ethanol, carbon dioxide, and hydrogen gases that may also be
formed during the Methyl-Red test
are detected in the
test.
A. True
B. False
B. False
Enterobacter forms ____ and ______, compounds that do not lower the
pH of the medium.
A. Ethanol and 2,3 butanediol
B. 2,3
butanediol and acetylmethyl carbinol
C. 2,3 butanediol and
(acetoin)
D. α-naphthol and KOH
E. None of the above
A. Ethanol and 2,3 butanediol
Although there is no test to detect _____, the presence of its
precursor, _______can be detected by
the Voges-Proskauer
test.
A. 2,3 butanediol, acetylmethyl carbinol
B. 2,3
butanediol, (acetoin)
C. α-naphthol, KOH
D. A and B
E.
None of the above
D. A and B
In the Voges-Proskauer test, ___________are added to the MR-VP broth.
The components of the
__________, react with the acetoin to yield
products that produce a brick-red color.
A. Barritt’s
Reagents
B. α-naphthol and KOH
C. 2,3 butanediol,
(acetoin)
D. α-naphthol, KOH
E. A and B
E. A and B
The formation of gases is detected in the Voges-Proskauer
test.
A. True
B. False
B. False
During the MR-VP test, an inoculated tube should be broth incubated
at 37°C for _____.
A. 1 to 5 days
B. 2 to 5 days
C. 3
to 5 days
D. 4 to 5 days
E. None of the above
B. 2 to 5 days
Barritt’s A reagent is α-naphthol and Barritt’s B reagent is
KOH
A. True
B. False
A. True
All bacteria can utilize citrate as their sole carbon and energy
source.
A. True
B. False
B. False
Simmon’s citrate is used to determine a nitrogen and energy source
for microbial metabolism.
A. True
B. False
B. False
Simmon’s citrate contains sodium potassium as the only source of
carbon.
A. True
B. False
B. False
Ammonia present in Simmon’s citrate supplies the nitrogen
source
A. True
B. False
B. False
Addition of nitrogen to Simmon’s citrate would supply another carbon
source besides citrate.
A. True
B. False
B. False
Simmon’s citrate contains trypan blue, a pH indicator that is green
at neutral pH but turns blue under
alkaline conditions (pH
greater than 7.6).
A. True
B. False
B. False
Since citrate utilization occurs under______, a slanted medium is
used to maximize the surface area and
contact with
oxygen.
A. anaerobic conditions
B. microaerophile
conditions
C. aerobic conditions
D. none of the
above
E. all of the above
C. aerobic conditions
The _____ in Simmon’s citrate medium is transported into the
bacterial cell by citrate permease and then
hydrolyzed by citrase
to form an acid and a gas.
A. citrate
B. pyruvic
acid
C. carbon dioxide
D. none of the above
E. all of
the above
A. citrate
The _____produced during the Simmon’s citrate test diffuses out of
the cell and reacts with Sodium ion
and water in the medium to
form compounds such as sodium carbonate, which raise the pH of
the
medium.
A. citrate
B. pyruvic acid
C. carbon
dioxide
D. none of the above
C. carbon dioxide
The alkaline conditions of a positive Simmon’s citrate test causes
the bromothymol blue to change the
medium color from green to
blue.
A. True
B. False
A. True
The inoculated Simmon’s citrate tube should be incubated at 37° C for
_____
A. 2 to 5 days
B. 1 to 2 days
C. 72 hours
D.
4 to 5 days
E. None of the above
B. 1 to 2 days
In the absence of a color change, evidence of growth on the slant is
indicative of a positive
Simmon’s citrate test
A.
True
B. False
A. True
Why is Simmon’s citrate used as a “slant”?
A. Maximize surface
area for CO2 exchange
B. Maximize surface area for H20
exchange
C. Maximize surface area for O2 exchange
D.
Maximize surface area for carbon exchange
E. None of the above
C. Maximize surface area for O2 exchange
Inoculate a tube of Nutrient Gelatin using a sterilized inoculating
needle. Stab the medium
straight down and pull it straight
out.
A. True
B. False
A. True
Gelatinase is an example of an:
A. Endoenzyme
B.
Exoenzyme
C. Apoenzyme
D. Coenzyme
E. None of the above
B. Exoenzyme
A molecule of starch is composed of two glucose polymers: ___ and
____.
A. alpha-D-glucose and amylose
B. amylopectin and
alpha-D-glucose
C. amylose and amylopectin
D. All of the
above
E. None of the above
C. amylose and amylopectin
Amylose is branched chain polymer, and amylopectin is
straight.
A. True
B. False
B. False
Bacteria that possess the enzyme amylase are able to split the starch
molecule into shorter
polysaccharide subunits called ____, ____,
and ____.
A. Dextrins, glycogen, glucose
B. Dextrins,
sucrose, glucose
C. Dextrins, maltose, glucose
D. Dextrins,
fructose, glucose
E. None of the above
C. Dextrins, maltose, glucose
Amylase belongs to the general class of enzymes called _____that use
a water molecule to split
their substrates into smaller end
product molecules.
A. Deoxyribonucleases
B.
Isomerases
C. Hydrolases
D. Enolases
E. None of the above
C. Hydrolases
Starch molecules are too small to enter the bacterial cell, and must
be digested outside the cell.
A. True
B. False
B. False
Some bacteria secrete amylase that acts as an _____since it is
secreted to the outside of the cell
where it can hydrolyze the
starch into smaller molecules that can be transported into the
cell.
A. Exoenzyme
B. Endoenzyme
C. Secreted
enzyme
D. Apoenzyme
E. A and C
E. A and C
End-product molecules of starch hydrolysis can be used by the
bacteria for use in energy
yielding, metabolic processes.
A.
True
B. False
A. True