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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5337_Библиотеки_им_академика_М_И_Перельмана.pdf
45. The presence of viruses in the bloodstream is
knownas:
A. Viraemia B. Bacteraemia
C. Septicaemia D. Pyemia
46. InGram-staining,iodineisusedasa___________.
A. Fixative B. Mordant
C. Solublizer D. Stain
47. Acridine dyes are more effective against:
A. Gram-positive B. Gram-negative
C. Shiella D. Mycoplasma
48. The percentage of alcohol used in Gram staining
is:
A. 75% B. 90%
C. 60% D. 25%
49. Gram-positive bacteria appear as:
A. Pink B. Violet
C. Both A and B D. None of these
50. Ifmorethan onestainis used,suchstaining is
called:
A. Simple staining
B. Negative staining
C. Differential staining
D. None of the above
51. Theenrichmentmediaforsalmonellaeisa/an:
A. Alkaline peptone B. Nutrient broth
C. Bile broth D. Serum agar
52. Symbionts are:
A. Bacteria in symbiotic association
B. The group of fungi in symbiotic association
C. The groups participating in symbiotic
association
D. All of the above
53. The microorganism engulfed by phagocyte resides
inavacuoleisknownas:
A. Phagosome B. Lysosome
C. Both A and B D. None of these
54. Attenuation means:
A. The killing of the bacteria or microbes
B. Inactivation of bacteria
C. More activating the bacteria
D. Both A and B
55. The main cause for cholera is:
A. Poverty and insanitation
B. Mosquitoes
C. Toxin produced by pesticides
D. None of the above
56. Themajorrole of minorelements inside living
organisms is to act as:
A. Cofactors of enzymes
B. Building blocks of important amino acids
C. Constituents of hormones
D. Binder of cell structure
57. The action of alcohol during Gram staining is:
A. Allows the colour
B. It adds colour
C. Decolourizes the cells
D. None of the above
58. The apparatus used to maintain a continuous
cultureis/are:
A. Chemostat B. Autostat
C. Thermostat D. Both A and C
59. Carriersarecalledchroniccarriers,iftheycontinue
to shed the causative agent:
A. Up to one month after clinical cure
B. Up to three months after clinical cure
C. Less than a year after clinical cure
D. For over a year after clinical cure
60. Virion means:
A. Infectious virus particles
B. Non-infectious particles
C. Incomplete particles
D. Defective virus particles
61. Antibodiesagainsttyphoid,paratyphoidAandB
fevers can be detected at:
A. 2–3 days of the disease
B. 4–5 days of the disease
C. 6–7 days of the disease
D. 8–10 days of the disease
62. Prophylaxis of cholera is:
A. Protected water supply
B. Environmental sanitation
C. Immunization with killed vaccines
D. All of the above
ANSWER KEY
1. B 2. C 3. C 4. D 5. C 6. D 7. B 8. C 9. B 10. A 11. C 12. C 13. B 14. C
15. B 16. A 17. D 18. C 19. C 20. B 21. C 22. D 23. A 24. B 25. A 26. A 27. A 28. C
29. A 30. A 31. D 32. B 33. B 34. B 35. C 36. B 37. C 38. C 39. D 40. D 41. B 42. C
43. D 44. D 45. A 46. B 47. A 48. B 49. D 50. C 51. C 52. C 53. A 54. B 55. A 56. A
57. C 58. A 59. D 60. C 61. D 62. D
Section 5 Microbiology
469468
4. Biology of Microorganisms
CULTURE TECHNIQUE
A population of bacteria grown in the laboratory is referred
to as a culture.
Pure culture: A culture containing a single type of
organism. It is usually developed from a mixed culture.
If a bacterial culture remains kept in the same media for
a long duration, the cells use up the available nutrients,
excrete toxic substances, and as result the entire population
will die. Thus, bacterial cultures must be periodically
transferred, to new culture media to keep the bacterial
population continuous growing.
Description of Colonial Morphology of Bacteria:
Texture—how the surface of the colony appears, e.g.
smooth, glistening, mucoid, slimy, dry, powdery, flaky, etc.
Transparency—colonies may be transparent, translucent,
or opaque.
Color—many bacteria produce intracellular pigments
which cause their colonies to appear a distinct colour.
General Protocol for Growing (or “Culturing”) Bacteria
Pouring media “plates”
“Streaking” bacteria on media plates
“Picking” a “colony” from the plate
“Inoculating” a liquid culture
Size of a Bacterial Cell
Various sizes ranges 0.75–1.5 µ.
The smallest rod-shaped eubacteria—Dialister
Sulphur bacteria—Thiophysa
Shape and Arrangement of Bacterial Cell
1. Round-shaped cocci—spherical cell
Micrococci—single bacterium
Diplococci—appears in pairs of cells
Streptococci—appears in chain form
Tetrad—appears in the square of four
Sarcinae—When arranged in cuboidal or in different
geometrical or packet arrangement
Staphylococci—Arranged in irregular clusters like
bunch of a grapes
2. Rod-shaped
Short rods—occurring mostly singly
Long rods—cylindrical shape, are known as Bacilli or rods
3. Vibrios—comma-shaped
4. Spirilla—spiral-shaped cells.
5. Spirochete
Different size, shape and arrangement of bacterial cells
Section 5 Microbiology
Types of media
S. No. Types Description Examples Use
1. Basal
media
2. Enriched
media
3. Selective
media
4. Indicator
(differential)
media
5. Transport
media
6. Storage
media
Basal media are simple media that
supports most non-fastidious bacteria
Peptone water, nutrient broth and
nutrient agar (NA) are considered as
basal medium
The media are enriched usually by
adding blood, serum or egg
Selective media are agar based. Any
agar media can be made selective by
the addition of certain inhibitory agents
that do not affect the pathogen of
interest. Various approaches to making
a medium selective include addition of
antibiotics, dyes, chemicals, alteration of
pH or a combination of these
An indicator is included in the medium.
A particular organism causes a change
in the indicator, e.g. blood, neutral red,
tellurite
Clinical specimens must be transported
to the laboratory immediately after
collection to prevent overgrowth
of contaminating organisms or
commensals. This can be achieved
by using transport media. Such
media prevent drying (desiccation) of
a specimen, maintain the pathogen
to commensal ratio and inhibit the
overgrowth of unwanted bacteria
Media used for storing the bacteria for a
long period of time
Nutrient broth, nutrient
agar and peptone
water
Blood agar and
Lowenstein-Jensen
media
MacConkey agar,
Lowenstein-Jensen
media, tellurite media
Blood agar and
MacConkey agar are
indicator media
Cary-Blair medium,
Stuart medium
Egg saline medium,
chalk cooked meat
broth
May be used for growth
(culture) of bacteria that
do not need enrichment
of the media
Enriched media
are used to grow
nutritionally exacting
(fastidious) bacteria
These media favour the
growth of a particular
bacterium by inhibiting
the growth of undesired
bacteria and allowing
the growth of desirable
bacteria
Certain media are
designed in such a way
that different bacteria
can be recognized
based on their colony
colour
These media are used
when specimen cannot
be cultured soon after
collection
Media is used for
storing the bacteria for
a long period of time
Bacterial Growth Curve
The bacterial growth curve represents the number of live
cells in a bacterial population over a period of time. Growth
is by geometric progression: 1, 2, 4, 8, etc. or 20, 21, 22,
23.........2n (where n = the number of generations). This is
called exponential growth. There are four different phases
of the growth curve.
Phase I: Lag, when a population of cells of bacteria is
introduced into the new fresh growth medium, they take
some time to adjust to the new environment. Phase where
cells are in the metabolically active (increase in size) stage
but not in dividing. The time duration of the lag phase
depends directly on the previous growth condition of the
organism.
Phase II: Exponential (log), is a time of exponential growth
in this phase cells, are in a rapidly dividing stage. After each
generation time cells doubled in numbers after dividing
by binary fission. In this phase, metabolic activity of cells
are very high. DNA, RNA, cell wall components, and other
necessary substances required for growth are produced.
Antibiotics and disinfectants are most effective in this
phase of bacterial cells because as these substances usually
target bacteria cell walls or the protein synthesis processes
of DNA transcription and RNA translation. The generation
time tends to vary with organism to organism, e.g. E. coli
divides in every 20 minutes, hence its generation time is
20 minutes, and for Staphylococcus aureus, it is 30 minutes.
Phase III: Stationary, growth reaches a plateau as the
number of dying cells equals the number of dividing
cells. This results in no overall population growth in
less acceptable or unfavourable conditions competition
for nutrients increases between the cells. Spore forming
bacteria produce endospores in this phase.
Phase IV: Death is characterized by an exponential
decrease in the number of living cells due to less availability
of nutrients and presence excess of waste products. In
Section 5 Microbiology
471470
this phase whena cell dies its contents spill into the
environment and these nutrients are available to other
bacteria. This helps spore producing bacteria to survive
long enough for spore production.
Bacterial growth curve
Bacterial transformation
Horizontal Gene Transfer Methods
Horizontal gene transfer (HGT) or lateral gene transfer
is the movement of genetic material (DNA or RNA)
between bacterial or eukaryotic cells but not in offspring.
HGT has a very important role in bacterial evolution.
This is also the reason by which bacteria have gained
antibiotic resistance and virulence. There are following
different ways to perform HGT, are:
z
Transformation
z
Transduction
z
Bacterial conjugation
Transformation, transduction, and conjugation occur
in nature as forms of HGT, but transfection is unique
to the lab.
Transformation
It is an uptake of genetic material (DNA fragment from
a dead, degraded bacterium) from the surrounding
environment by bacterial cells.
In the nature occurring method, this genetic material
often comes from adjacent broken bacteria and can
include plasmid DNA or fragmented DNA released into
the environment.
Though not all bacteria are naturally competent to
take up DNA, they can be made competent through
chemical manipulation in the lab. This is commonly done
using calcium chloride which permeabilizes the cell
membrane so the bacteria can easily uptake your plasmid
of interest.
Transduction
Transduction is the transfer of genetic information from a
donor to a recipient by way of a bacteriophage. The phage coat
Section 5 Microbiology
protects the DNA in the environment so that transduction,
unlike transformation, is not affected by nucleases in the
environment. Not all phages can mediate transduction.
Transduction occurs with the help of a virus or bacteriophage in which a piece of foreign DNA or RNA is
inserted into bacterial or eukaryotic cells.
Phages can follow one of two different life cycles: Lytic
or lysogenic
Lytic phages hijack the bacterial host’s machinery to make
more viral particles. Eventually, the cell lyses release
the newly formed viral particles that can infect other
bacteria.
In the lysogenic cycle, the phage’s genetic material is
incorporated into the host’s genome at a particular
integration site. The integrated phage remains dormant
until it is triggered to enter the lytic cycle.
Types of Transduction
Generalized transduction: Generalized transduction is
transduction in which potentially any bacterial gene from
the donor can be transferred to the recipient.
Specialized transduction: Specialized transduction is
transduction in which only certain donor genes can be
transferred to the recipient.
Bacterial Conjugation
During conjugation, genetic material is transferred from
a donor cell to a recipient cell through direct or cell-tocell contact.
The donor bacterium contains a DNA sequence called
the fertility factor (F-factor).
The F-factor is found on an episome, a piece of DNA
that can replicate on its own or be integrated within a
bacterial chromosome and allows the donor bacterium
to make a small “bridge” or sex pilus that attaches to
the recipient cell drawing it close. Once in contact, the
donor can transfer genetic material to the recipient
bacterium.
Generalized transduction
Step I: Bacteriophages attachment to the bacterial membranes, infects
bacterial cell
Step II: Penetration of their genetic material into the donor cell
Step III: Degradation or hydrolyzation of chromosomal DNA into pieces
and phase DNA and proteins are made
Step IV: Assembly of bacteriophage which occasionally carries
bacterial DNA and cause cell lysis
Step V: Attachment and penetration of bacteriophage that carries
donor cell DNA into the recipient cell
Step VI: Recombinant DNA which carries phase DNA and the recipient
chromosomal DNA
Specialized transduction
Section 5 Microbiology
473472
MULTIPLE CHOICE QUESTIONS
1. Intheclassicationofbacteriaaccordingtoshape,
whichamongthefollowingrefertothecuboidal
arrangement of bacterial cells?
A. Tetrads B. Staphylococci
C. Sarcinae D. Streptococci
2. Minimumgrowthtemperatureis:
A. The growth of organisms at the lowest
temperature
B. The lowest temperature at which the
microorganisms grow
C. The maximum temperature at which the growth
is stable
D. None of the above
3. The smallest cell of mycoplasmas is about
__________ in diameter.
A. 1 micrometre B. 0.3 micrometre
C. 5 micrometre D. 1 metre
4. The generation time for E. coli is ________.
A. 20 minutes B. 35 minutes
C. 2 minutes D. 13 minutes
5. Roll-tube technique is used to isolate ___________.
A. Aerobes B. Anaerobes
C. Facultatives D. Stringent anaerobes
6. The principle in microbiological assays is:
A. At a certain range, the concentration of growth
factor will bear a linear relationship to the
amount of nutrients added
B. Concentration of growth factor has a linear
relationship with the growth of the organism
C. Both A and B
D. None of the above
7. Forthesynthesisofaminoacidscysteine,cystine
andmethionine,theelementrequiredis:
A. Sulphur B. Oxygen
C. Nitrogen D. None of these
8. Trace elements are:
+2
A. Zn
, Cu+2, Mn
B. Mo6+, Ni2+, B3+ and Co
+2
2+
C. Both A and B
D. None of the above
9. By pasteurization:
A. All the microorganisms can be removed
B. Only pathogenic forms can be removed
C. Only non-pathogenic forms can be removed
D. All of the above
10. The temperaturethat allowsthemost rapid
growthduringashortperiodoftimeisknownas
__________.
Section 5 Microbiology
A. Minimum temperature
B. Maximum temperature
C. Optimum temperature
D. Growth temperature
11. The vitamin required for Lactobacillus species is:
A. Riboflavin B. Niacin
C. Pyridoxine D. Folic acid
12. Radical shifts can be prevented by adding:
A. Acids B. Alkali
C. Buffer D. None of these
13. Differentialmediacontain allofthe following,
except:
A. Basal medium
B. Substances that inhibit microorganisms
C. Sugar concerned
D. Indicator
14. Which ofthe followingisa richsource of B
vitamins?
A. Peptone B. Yeast extract
C. Beef extract D. All of these
15. Whichofthefollowingarefunctionsofwaterin
the culture medium?
A. Nutrients must be in an aqueous solution
B. Cofactor of enzymes
C. Provides resistance to sudden transient
temperature changes
D. It is a chemical reactant; nutrients must also be
present in an aqueous solution and provides
resistance to sudden temperature changes
16. Howmuchtimedobacteriatakeforthecomplete
duplication?
A. 30 minutes B. 10 minutes
C. 20 minutes D. 25 minutes
17. Inbacteria,theincreaseinpopulationtakesplace
inwhichofthefollowingmanner?
A. Geometric progression
B. Multiplication
C. Doubling
D. None of the above
18. Whichofthefollowing reactiveoxygenspecies
(ROS)isapowerfuloxidisingagent?
A. Superoxide radical
B. Hydrogen peroxide
C. Hydroxyl radical
D. Singlet oxygen
19. Strict anaerobeslack whichof the following
enzymes?
A. Catalase
B. Peroxidase
C. Superoxide dismutase
D. All of the above
20. Logphaseisalsoknownas:
A. Death phase B. Exponential phase
C. Lag phase D. None of these
21. Rhodopseudomonas acidophila reproduces by
whichofthefollowingmethods?
A. Binary fission B. Budding
C. Fragmentation D. Sporulation
22. Cyclic phosphorylation is generally present in:
A. Cyanobacteria B. Algae
C. Bacteria D. Plants
23. Inwhich of thefollowing situations willthe
logarithmic plot of survivors be constant?
A. Physiological conditions are different
B. Cells of microbial population vary in size
C. Age and physiological conditions are uniform
D. Temperature conditions are different
24. Intheautoclave,theprincipleinvolvedis:
A. Dry heat
B. Moist heat
C. Steam under pressure
D. Both B and C
25. Cerebral malaria is caused by:
A. Plasmodium vivox B. P. ovale
C. P. falciparum D. P. malaria
26. Phosphorus is an essential component of
__________.
A. Teichoic acid
B. Nucleotides
C. Phospholipids
D. Teichoic acid, nucleotides, phospholipids
27. Mycotoxins are produced by:
A. Bacteria B. Fungi
C. Algae D. Protozoans
28. Whichof thefollowing does notoccur during
binaryssioninbacteria?
A. Cell elongation B. Cytokinesis
C. DNA duplication D. Spindle formation
29. Whichofthefollowingistherelationshipbetween
optical density and cell mass?
A. Exponentially proportional
B. Linearly proportional
C. Inversely proportional
D. Not related
30. TheLringinagram-negativebacteriumagella
isassociatedwith_________.
A. Peptidoglycan
B. Outer membrane
C. Cytoplasmic membrane
D. Cell membrane
31. Whichofthefollowingis/arefunction(s)ofthe
stalk?
A. Nutrient absorption
B. Motility
C. Attachment of the cells to surfaces
D. Human infection
32. Which amongthe followingcomeunder gram-
positive eubacteria?
A. Clostridium
B. Actinomyces
C. Rhizobium
D. Clostridium, Actinomyces
33. Inwhich ofthe following phasesecondary
metabolitesareproducedduringgrowth?
A. Lag phase
B. Log/exponential phase
C. Stationary phase
D. Death phase
34. Howmuchtimeisrequiredbytheyoungcellsto
be killed by a lethal agent?
A. 24 hours B. 3–4 hours
C. 30 minutes D. 5 minutes
35. Growthfactorsare:
A. Mineral salts
B. Ammonium salts
C. Hydrogen, carbon, nitrogen
D. Essential substances that bacteria cannot
synthesise by themselves
36. Bacteriathatcannotgrowinthepresenceofoxygen
are:
A. Strict anaerobes
B. Strict aerobes
C. Facultative anaerobes
D. Microaerophilic
37. Whichofthefollowingfactorsareresponsiblefor
the stability of thermophiles at high temperatures?
A. Increased leakage of cell components
B. Presence of large number of polar amino acids
and alpha-helix protein
C. Thermal stability of ribosomes
D. Presence of inositol diphosphate and thermal
stability of ribosomes
38. Whichofthefollowinghasalargerdiameter?
A. Well-separated colonies
B. Crowded colonies
C. Young colonies
D. Old colonies
39. Whichofthefollowingmethodsisusedforthe
enumeration of bacteria in vaccines and cultures?
A. Microscopic count
B. Membrane filter
C. Plate count
D. Dry weight determination
40. Whichgroupofbacteriaamongthefollowinghas
the largest area of contact?
A. Palisades B. Trichomes
C. Streptobacilli D. Diplobacilli
41. Agar is obtained from
A. Brown algae B. Red algae
C. Green algae D. Blue-green algae
42. Foreffective sterilizationin an autoclave,the
temperature obtained is:
A. 50°C B. 100°C
C. 120°C D. 180°C
Section 5 Microbiology
475474
43. Todifferentiatelactoseandnon-lactosefermenters,
the medium used is:
A. Wilson and lair
B. Blood agar
C. Tetrathionate broth
D. MacConkey’s agar
44. Thebacteriawhich areableto growat 0°C but
whichgrowat20°–30°C,areknownas:
A. Psychrophiles
B. Facultative psychrophiles
C. Average psychrophiles
D. Mesophiles
45. Which of these is a trace element for bacteria?
+2
A. Mg
B. Na
C. Ca+2 D. Mn
+
+2
46. Salts of heavy metals used as disinfectants are:
A. Thiomersal
B. Phenyl mercury nitrate
C. Mercurochrome
D. All of the above
47. Thetermthatisusedforthebacteriawhichcan
withstandpasteurization butdoes not growat
higher temperatures is:
A. Thermophiles
B. Extreme thermophiles
C. Thermoduric
D. Facultative thermophiles
48. A common laboratory method of cultivating
anaerobic microorganisms is:
A. Gas-pak system
B. Brewer jar system
C. Pyrogallic acid over the cotton
D. None of the above
49. Blood agar is a:
A. Differential media B. Enriched media
C. Selective media D. Simple media
50. Whichof the following isgas-producing
Salmonella?
A. S. typhi B. S. enteritidis
C. S. cholerasuis D. S. typhimurium
51. Culture medium for Mycobacterium tuberculosis:
A. L J medium
B. MacConkey’s medium
C. Wilson-Blair medium
D. None of the above
52. LowerSteinJensen’smedium:
A. Mac Conkey’s medium
B. Robertson’s cooked meat medium
C. None of the above
D. All of the above
53. Inpour-plate method,the mediumshould be
Section 5 Microbiology
maintainedatwhattemperature?
A. 37°C B. 67°C
C. 45°C D. 0°C
54. Culture medium used for fungus is:
A. Sabouraud’s medium
B. Nutrient agar
C. Nutrient broth
D. Minimal agar medium
55. Example of anaerobic medium is:
A. Wilson Conkey medium
B. MacConkey broth
C. Robertson’s cooked meat medium
D. EMB agar
56. Bacteria belonging to the family Bacteriodaceae
usewhichofthefollowingcompoundsaselectron
acceptors?
A. Oxygen B. Inorganic sulphur
C. Nitrate D. Phosphate
57. An example of competitive inhibition of an
enzyme is the inhibition of:
A. Succinic dehydrogenase by malonic acid
B. Cytochrome oxidase by cyanide
C. Hexokinase by glucose-6-phosphate
D. Carbonic anhydrase by carbon dioxide
58. Fpilushasamajorroleas___________
A. Motility of the cell
B. Port of entry of genetic material during mating
C. Attachment to host cell
D. Human infection
59. Virulent factor in pneumococcus is:
A. Cell wall B. Capsule
C. Mesosomes D. Endotoxins
60. Whichofthefollowingspeciesisassociatedwith
spoilage of canned goods?
A. B. stearothermophiles B. B. cereus
C. B. subtilis D. B. sphaericus
61. Nutrientagarispreparedbytheadditionof:
A. 0% agar in nutrient broth
B. 3% agar in nutrient broth
C. 5% agar in nutrient broth
D. 10% agar in nutrient broth
62. C. perfringens isthe majorcausative agent of
_______________.
A. Botulism B. Tetanus
C. Gas gangrene D. Anthrax
63. ThefollowingdiseasesarecausedbyMycoplasma,
except:
A. Pneumonia in human beings
B. Little leaf of brinjal
C. Dwarf disease of mulbery
D. Citrus canker
64. Theorganismswhichcanusereducedinorganic
compoundsas electron donorsare knownas:
_________
A. Chemotrophs B. Organotrophs
C. Lithotrophs D. Phototrophs
65. Which device is used to pick a single bacterial cell
from a mixed culture?
A. Microscope B. Micropipette
C. Microprobe D. Micromanipulator
66. The size of the virus can be determined by:
A. Micrography
B. Ultra-centrifugation at high speed
C. Ultra-filtration
D. All of the above
67. The average size of the cells in the exponential
phase is ___________.
A. Smaller than the initial size
B. Larger than the initial size
C. Equal to the initial size
D. May be smaller or larger than the initial size
68. Theportion ofthe growth curvewhere rapid
growthof bacteria isobserved isknown as
____________.
A. Lag phase B. Logarithmic phase
C. Stationary phase D. Decline phase
69. Whichofthefollowingnonsporeforminggram-
positiverodsshowanegativeresultsforcatalasetest?
A. Lactobacillus B. Kurthia
C. Brocothrix D. Renibacterium
70. Nutrient broth, a liquidmedia containsbeef
extractand peptone respectivelyin howmuch
amounts?
A. 0.2–0.4% B. 0.1–0.6%
C. 0.3–0.5% D. 0.3–0.7%
71. Theendoflagella ispresent in whichclass of
bacteria?
A. Spirilla B. Spirochetes
C. Bacillus D. Coccus
72. Bacteriawithlessthanacompletetwistorcomma-
shapeisknownas:
A. Spirilla B. Helical
C. Vibrioid D. Spirochetes
73. Growthofbacteria ormicroorganisms refersto
__________________.
A. An increase in the size of an individual
organism
B. An increase in the mass of an individual
organism
C. Changes in the total population
D. An increase in number of cells
74. Bacteriahavingaclusterofagellaatbothpoles
ofcellsareknownas:
A. Lophotrichous B. Peritrichous
C. Amphitrichous D. Monotrichous
75. Whichofthefollowingbacteriacangrowbothas
chemolithotrophs or as chemo-organotrophs?
A. Nitrosomonas sp.
B. Pseudomonas pseudoava
C. Rhodospirillum rubrum
D. Chromatium okenii
76. Whichofthe followingisa complexmedia for
fungalgrowth?
A. Nutrient broth
B. Luria-Bertani media
C. Potato dextrose agar (PDA) media
D. MacConkey agar media
77. Themajorconstituentsinagarare:
A. Fats B. Amino acids
C. Polysaccharides D. Polypeptides
78. Whichofthefollowing instruments isusedfor
sterilizing the media after it has been prepared?
A. Autoclave
B. Laminar air flow chamber
C. Inoculum needle
D. Incubator
79. Whichofthefollowingisacharacteristicofthe
beef extract?
A. Product resulting from the digestion of
proteinaceous materials
B. Aqueous extract of lean beef tissue
C. Aqueous extract of yeast cells
D. Complex carbohydrates obtained from certain
marine algae
80. Theisolation ofgonorrhea-causing organism,
Neisseria gonorrhoeae by the use of certain
antibioticsinmediaisanexampleofwhichofthe
following?
A. Selective media
B. Differential media
C. Enriched media
D. Assay media
81. Whichofthefollowingmethodsisusedforthe
viable count of a culture?
A. Direct microscopic count
B. Plate-count method
C. Membrane-filter count
D. Plate-count method and membrane-filter count
82. Nitritesareoxidizedtonitratesbyamicroorganism,
named as:
A. Nitrosomonas
B. Nitrosococcus
C. Nitrobacter
D. Azoatobacter
83. Which of the following is a nutritional
characterization of Escherichia coli?
A. Chemotrophic
B. Organotrophic
C. Autotrophic
D. Chemotrophic, organotrophic, heterotrophic
84. Whichof thefollowing are notperformed in
lyophilization?
A. Agar slant is covered with mineral oil
B. Cell suspension is frozen at –60° to –78°C
C. Vials are connected to high-vacuum line
D. Bacterial sample is dehydrated
Section 5 Microbiology
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85. TheoptimumpH rangeforthe growthofmost
bacteria is:
A. 5–9 B. 6.5–7.5
C. 2–3.5 D. 9–9.5
86. What is the approximate size of the bacterial cell?
A. 2 mm in diameter
B. 1 mm in diameter
C. 2 micrometer in diameter
D. 0.5–1.0 micrometer in diameter
87. Thefollowingorganismshavebeenproposedas
sources of single cell protein:
A. Bacteria B. Yeasts
C. Algae D. All of these
88. Lagphaseisalsoknownas___________.
A. Period of initial adjustment
B. Transitional period
C. Generation time
D. Period of rapid growth
89. Pyoverdiniswhichtypeofpigment?
A. Water-insoluble pigment
B. Water-soluble pigment
C. Fluorescent pigment
D. Sparingly water-soluble pigment
90. Biological oxygen demand (BOD) is a measure of:
A. Industrial wastes poured into water bodies
B. The extent to which water is polluted with
organic compounds
C. Amount of carbon monoxide inseparably
combined with haemoglobin
D. Amount of oxygen needed by green plants
during the night
91. Inthegrowthequationn=3.3(log10N–log10N
),
o
‘N’standsfor____________.
A. Total population
B. Initial population
C. Number of generations
D. Growth constant
92. Whichofthefollowingisnotaphysicalmethod
for the selection of pure culture?
A. Heat treatment
B. The pH of the media
C. Cell size and motility
D. Use of dilute media
93. Whichof the following are functions of
maintenance media?
A. Used for assay of vitamins, amino acids
B. Used for determining the bacterial content
C. Used for determining the type of growth
produced by bacteria
D. Used for the maintenance of the viability and
physiological characteristics
94. The reactive oxygen species (ROS) produced
bysome bacteria aredegraded by whichof the
followingenzymes?
A. Peroxidase
B. Lyase
C. Catalase
D. Superoxide dismutase, catalase and peroxidase
95. Mesophilesare agroup ofbacteria that grow
withinthetemperaturerangeof:
A. 0–20°C
B. 25–40°C
C. 45–60°C
D. >60°C
96. Whichofthefollowingis used asasolidifying
agent for media?
A. Beef extract
B. Peptone
C. Agar
D. Yeast extract
97. Prosthecae help in __________.
A. Nutrient absorption and attachment to surfaces
B. Motility
C. Human infection
D. Protection from environment
ANSWER KEY
1. C 2. B 3. B 4. A 5. D 6. B 7. D 8. D 9. B 10. C 11. B 12. C 13. B 14. B
15. D 16. C 17. A 18. B 19. D 20. C 21. B 22. A 23. C 24. D 25. C 26. D 27. B 28. D
29. B 30. B 31. C 32. D 33. C 34. C 35. D 36. A 37. D 38. A 39. A 40. B 41. B 42. C
43. D 44. C 45. B 46. D 47. C 48. C 49. B 50. D 51. A 52. B 53. C 54. B 55. C 56. C
57. A 58. B 59. D 60. A 61. B 62. C 63. C 64. C 65. D 66. D 67. A 68. B 69. A 70. C
71. B 72. C 73. D 74. C 75. B 76. C 77. C 78. A 79. B 80. A 81. D 82. C 83. D 84. A
85. B 86. D 87. D 88. A 89. C 90. A 91. C 92. D 93. D 94. D 95. B 96. C 97. A
Section 5 Microbiology