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