Microbiology Midterm Flashcards

1
Q

phase microscopy is best used for

A

live cells

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2
Q

bacteria in milk can survive pasteurization temperatures and cause spoilage or souring of milk, these bacteria are called

A

thermodurics

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3
Q

what allows bacteria to normally survive hypotonic solutions

A

cell wall

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4
Q

what is the average ratio of bacteria to human cells in the human body

A

10 to 1

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5
Q

osmophiles are organisms that can grow

A

at high concentration of sugar

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6
Q

what is the bacterial arrangement term for cocci arranged in clusters

A

staphylococcal

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7
Q

while trying to view a specimen under the light microscope, turning the coarse or fine focus knows adjusts the distance between which of the following parts

A

the stage and the objective lenses

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8
Q

these kinds of bacteria use aerobic respiration to make their energy but can only tolerate very low concentrations of oxygen

A

microaerophiles

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9
Q

some bacteria can grow at 4C and can cause food spoilage they are called

A

psychrotrophs

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10
Q

Gram’s iodine is added to the Gram stain procedure for what reason

A

it combines with the crystal violet and forms an insoluble complex in Gram positive cells

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11
Q

in a typical light microscope, what are the series of lenses that focus light onto the specimen called

A

condenser

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12
Q

when we say bacteria are ubiquitous, we mean

A

they are found everywhere

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13
Q

IMViC tests are used to

A

differentiate between E. coli and E. aerogenes

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14
Q

what type of slides would you most likely look at with phase-contrast microscopy

A

wet mount slides

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15
Q

what type of media would you use for the growth of fastidious organisms

A

enriched media

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16
Q

which type of organism does NOT need oxygen and is NOT poisoned by it

A

aerotolerant

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17
Q

what are the two types of light rays important for phase contrast microscopy

A

direct rays and diffracted rays

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18
Q

which of the following microorganisms would you NOT be able to observe using light microscopy

A

ultramicrobacteria (184 nm long, shorter than other options)

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19
Q

coliforms have which of the following characteristics

A
  • gram negative
  • facultative anaerobes
  • non-endospore forming rods
  • ferment lactose to produce gas
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20
Q

most human pathogens belong to what group of bacteria

A

mesophiles

21
Q

who developed the phase contrast microscope

A

Frits Zernike

22
Q

if you transfer 1 mL of culture into 99mL of sterile water and then add 0.1 mL of that to an agar plate, what is the final dilution of the culture on that plate

23
Q

respiration uses what as the terminal electron acceptor

24
Q

endospores are highly resistant to heat, radiation, acids and many chemicals because of their protective protein coating known as

A

exosporium

25
after the alcohol step in the gram stain procedure, what color will gram negative bacteria be
clear
26
why might a bacterial culture give Gram-variable results
- the culture is too old - the culture is a Bacillus species - the smear is too thick - it was over decolorized
27
acid-fast staining is used
when the bacteria have a high mycolic acid content
28
Brownian motion is caused by
Bombarding molecules
29
as you increase the magnification, __________ decreases
- the field of view | - the working distance
30
which of these tests is not matched correctly with a material used in the test
confirmed test .... tryptone glucose extract agar correct: - presumptive test ... lactose broth - presumptive test ... durham dube - confirmed test ... endo broth - confirmed test ... EMB agar
31
which of these can NOT be measured by a spectrophotometer
Most probable number
32
which of the following environments is most likely to cause plasmolysis
hypertonic
33
what's the most critical step of the gram stain
using the alcohol
34
which setting should the condenser be on when looking at bacteria under oil immersion using phase contrast microscopy
3 (x100?)
35
which of the following is NOT a part of a bacterial flagellum
N-ring yes: - filament - L-ring - S-ring - hook
36
motility medium can be used to determine if bacteria are motile because
it has an agar concentration of ~ 0.4%
37
where would you NOT normally find bacteria among the following
your blood
38
your light microscope has a limit resolution of (??)
0.2 micrometers
39
which of these statements is true
-the presence of microorganisms in food doesn't mean it has potential to cause disease
40
it is easier to test water for presence of indicator bacteria such as
E. coli
41
microorganisms used enzymes like catalase and peroxidase to
convert toxic oxygen forms to less harmful compounds
42
Thermodurics are bacteria capable of what?
survival at high temperature
43
which of these is a reason microbiologists use acid-fast staining
able to stain cells with a high lipid content cell wall
44
which of the following is an example of a bacterium that is present in the form of a tetrad cocci
micrococcus leteus
45
the telescopic eyepiece is used for
aligning the phase rings
46
what is the bacterium that has two bundles of flagella at opposite poles called
amphitrichous
47
which of these techniques is used in the isolation of pure bacterial cultures
streak plate
48
what is the cell wall of bacteria composed of
peptidoglycan
49
what microscope part should never be used with the two highest power objectives
coarse focus know