Cell Cultures and Characteristics
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For
the selection of lactobacilli present in cheddar cheese, the pH of the medium
is maintained at ___________.
a.
6.35
b. 5.35
c.
4.35
d.
5.75
A
disease producing species occurring in a mixed culture can often be selected on
the basis of its ___________.
a. pathogenic
properties
b.
special carbon source
c.
special nitrogen source
d.
none of these
Important
example(s) of enriched medium/media is/ are ___________.
a.
Loeffler's serum slope
b.
Bordet-gengou medium
c.
Blood agar
d. All of these
Cell
counting can be carried out by ___________.
a.
direct microscopic count using petroffhansser counting chamber
b.
plate counting
c.
membrane filter count
d. all of the above
The
solidifying agent commonly used in preparation of media is/are ___________.
a.
agar
b.
silica gel
c. both (a) and (b)
d.
none of these
Which
of the following bacteria can grow in acidic pH?
a.
Vibrio cholerae
b. Lactobacilli
c.
Shigella
d.
Salmonella
Cell
size and cell number can be measured using ___________.
a.
hemocytometer
b. coulter counter
c.
petroff-hausser counting chamber
d.
none of these
For
the selection of endospore-forming bacteria, a mixed culture can be heated at ___________.
a. 80°C for 10
minutes
b.
70°C for 10 minutes
c.
60°C for 10 minutes
d.
90°C for 10 minutes
The
concentration of agar to obtain semi solid media is ___________.
a.
1.5-20%
b. 0.5% or less
c.
>10%
d.
>10%but<20%
Which
of the following bacteria dies quickly after drying?
a. Treponema
pallidium
b.
Mycobacterium tuberculosis
c.
Staphylococcus aureus
d.
Pseudomonas aeruginosa
Mac-Conkey
medium is an example of ___________.
a.
transport medium
b.
enrichment medium
c. differential
medium
d.
all of these
Pseudomonas
aeruginosa forms a blue water soluble pigment called ___________.
a. pyocyanin
b.
chlororaphin
c.
pyoverdin
d.
β-carotene
Agar
is used for solidifying culture media because ___________.
a.
it does not affect by the growth of bacteria
b.
it does not add to the nutritive properties of the medium
c.
the melting and solidifying points of agar solution are not the same
d. all of the above
Which
of the following is used for the proper maintenance and preservation of pure
cultures?
a.
Periodic transfer to fresh media
b.
Preservation by overlaying cultures with mineral oil
c.
Preservation by lyophilization
d. All of the above
In
the process of freeze drying, a dense cell suspension is placed in small vials
and is frozen at ___________.
a. -60 to -78°C
b.
-20 to -30°C
c.
-30 to -48°C
d.
-48 to -58°C
Which
of the following chemotherapeutic agents may affect the growth of Campylobacter
jejuni?
a.
Vacomycin
b.
Polymyxin
c.
Trimethoprim
d. None of these
To
select cholera-causing bacterium, Vibrio cholerae, the pH of the medium is
maintained at a pH of ___________.
a. 8.5
b.
8.90
c.
6.79
d.
3.5
Which
of the following techniques may be performed quantitatively to determine the
number of bacteria of a particular type?
a.
Pour plate
b.
Spread plate
c. Both (a) and (b)
d.
Streak plate technique
Intestinal
bacteria can grow in the presence of __________ whereas nonintestinal bacteria
are usually inhibited.
a. bile salts
b.
low concentration of various dyes
c.
sugars
d.
low levels of nitrogen
Which
of the following problem makes it impossible to satisfy all of Koch's
postulates?
a.
Microorganism causes serious symptoms in humans
b. Microorganism
cannot be isolated in pure culture
c.
Species of microorganism is in question
d.
Genes from the microorganism cannot be amplified by PCR
A
medium containing crystal violet dye plus sodium deoxycholate will allow ___________.
a. gram (-)ve
intestinal bacteria to grow
b.
gram (+)ve intestinal bacteria to grow
c.
aquatic bacteria to grow
d.
none of these
Stuart's
transport medium is used for transport of specimen containing ___________.
a. Neisseria
gonorrhoeae
b.
Salmonella
c.
Vibrio cholerae
d.
Shigella
Plate
counts are often reported as ___________.
a.
cfu
b. cfu/ml
c.
Both (a) and (b)
d.
thousands/ml
The
medium which allows the growth of more than one microorganisms of interest but
with morphologically distinguishable colonies is known as ___________.
a.
selective medium
b.
enrichment medium
c. differential
medium
d.
none of these
Selective
media facilitate growth of only one kind of organism. Saboraud medium is used
to selectively isolate ___________.
a.
coliform bacteria
b.
gram positive bacteria
c. yeasts
d.
acid fast organisms
Which
of the following bacteria can grow in alkaline pH?
a.
Shigella
b.
Lactobacilli
c.
Salmonella
d. Vibrio cholerae
All
bacteria that inhabit the human body are ___________.
a. heterotrophs
b.
chemolithotrophs
c.
autotrophs
d.
phototroph
When
a substance is added to a liquid medium which inhibits the growth of unwanted
bacteria and favors the growth of wanted bacteria, it is known as ___________.
a.
differential medium
b.
enriched medium
c. enrichment medium
d.
selective medium
Which
of the following methods is most likely to be quantitative?
a. Dilution and
plating
b.
Gram staining
c.
Wet mount
d.
None of these
Which
of the following hint(s) suggest/s that a given specimen is likely to contain
anaerobic bacteria?
a.
Gas in specimen
b.
Foul odour
c.
Presence of sulphur granules
d. All of these
Viable
plate count can be obtained using ___________.
a.
Spread plate method
b.
Pour plate method
c. both (a) and (b)
d.
Hemocytometer
In
the pour plate method, the mixed culture is diluted directly in tubes of ___________.
a. liquid agar medium
b.
sterile liquid usually water
c.
both (a) and (b)
d.
none of these
Treponema
species from human oral cavity can be selected by using ___________.
a.
pH of the medium
b.
incubation temperature
c. cell size and
motility
d.
all of these
When
a substance is added to a solid medium which inhibits the growth of unwanted
bacteria but permits the growth of wanted bacteria, it is known as ___________.
a.
differential medium
b.
enriched medium
c.
enrichment medium
d. selective medium
Peptone
water and nutrient broth are ___________.
a.
selective media
b.
enriched media
c. basal media
d.
none of these