MICROBIOLOGY LAB PRACTICAL EXAM
Mixed culture - answer-microbial culture consisting of two or more species
Pure culture - answer-microbial culture consisting of only a single species
Streak plate isolation - answer-bacterial sample is streaked over the surface of a
plated agar medium. During streaking, cell density decreases, leading to individual
cells being deposited separately on agar surface
Free-living microorganisms - answer-microorganisms that do not reside on or in a
specific plant or animal host and are not known to cause disease; nonpathogenic
Pathogens - answer-microorganisms that cause disease; associated with their
host(s)
Opportunistic pathogens - answer-capable of producing a disease state if introduced
into a suitable part of the body
,Reservoir - answer-any area, including sites outside of host organism, where a
microbe resides and serves as a potential source of infection
Colony - answer-visible mass of cells
Basic categories of colony morphology - answer-colony shape, margin (edge),
elevation, texture, and pigment production (color)
Shape category - answer-round, irregular, or punctiform (tiny, pinpoint)
Margin category - answer-entire (smooth w/ no irregularities), undulate (wavy), lobate
(lobed), filamentous, rhizoid (branched like roots)
Elevation category - answer-flat, raised, convex, pulvinate (very convex), umbonate
(raised in center)
Texture category - answer-moist, mucoid, dry
Pigment production (color) category - answer-opaque, translucent, shiny, or dull
What is the purpose of doing a quadrant streak plate? - answer-it is the initial streak
for isolation of 2+ bacterial species in a mixed culture with suspected high cell
density
Briefly describe procedure of quadrant streak plate - answer-1. Obtain bacterial
species sample with sterile inoculating loop
2. Drag loop left to right on one side of agar surface
3. Sterilize loop
,4. Drag loop from one end to another
5. Repeat two times
6. Incubate
Parts of the microscope - answer-
Condenser lens - answer-concentrates light and makes illumination of the species
more uniform
What produces a magnified real image? - answer-refraction of light as it passes
through the objective lens from the specimen
What happens at the ocular lens? - answer-image gets magnified again
What does the ocular lens produce? - answer-virtual image that appears below or
within the microscope
Total magnification of a microscope objective - answer-(magnification by objective
lens) x (magnification by ocular lens)
Magnification of ocular lens - answer-10x
What happens to image clarity as magnification increases? - answer-image clarity is
more difficult to maintain
Resolution - answer-clarity of an image
, Limit of resolution - answer-resolving power
Limit of resolution/resolving power - answer-actual measurement of how far apart
two points must be for the microscope to view them as being separate
What happens to resolution as the limit of resolution is made smaller? - answer-
resolution improves
Numerical aperture - answer-measure of a lens's ability to "capture" light coming
from the specimen and use it to make the image
What does immersion oil do to numerical aperture? - answer-increases numerical
aperture
What does immersion oil do to limit of resolution? - answer-makes limit of resolution
smaller
Dark field microscopy - answer-special condenser is used so only the light reflected
off the specimen enters the objective; brightly lit specimen in dark background;
better resolution
Phase contrast microscopy - answer-special optical components to exploit subtle
differences in the refractive indices of water and cytoplasmic components to produce
contrast
Fluorescence microscopy - answer-uses fluorescent dye that emits fluorescence
when illuminated with uv radiation
Mixed culture - answer-microbial culture consisting of two or more species
Pure culture - answer-microbial culture consisting of only a single species
Streak plate isolation - answer-bacterial sample is streaked over the surface of a
plated agar medium. During streaking, cell density decreases, leading to individual
cells being deposited separately on agar surface
Free-living microorganisms - answer-microorganisms that do not reside on or in a
specific plant or animal host and are not known to cause disease; nonpathogenic
Pathogens - answer-microorganisms that cause disease; associated with their
host(s)
Opportunistic pathogens - answer-capable of producing a disease state if introduced
into a suitable part of the body
,Reservoir - answer-any area, including sites outside of host organism, where a
microbe resides and serves as a potential source of infection
Colony - answer-visible mass of cells
Basic categories of colony morphology - answer-colony shape, margin (edge),
elevation, texture, and pigment production (color)
Shape category - answer-round, irregular, or punctiform (tiny, pinpoint)
Margin category - answer-entire (smooth w/ no irregularities), undulate (wavy), lobate
(lobed), filamentous, rhizoid (branched like roots)
Elevation category - answer-flat, raised, convex, pulvinate (very convex), umbonate
(raised in center)
Texture category - answer-moist, mucoid, dry
Pigment production (color) category - answer-opaque, translucent, shiny, or dull
What is the purpose of doing a quadrant streak plate? - answer-it is the initial streak
for isolation of 2+ bacterial species in a mixed culture with suspected high cell
density
Briefly describe procedure of quadrant streak plate - answer-1. Obtain bacterial
species sample with sterile inoculating loop
2. Drag loop left to right on one side of agar surface
3. Sterilize loop
,4. Drag loop from one end to another
5. Repeat two times
6. Incubate
Parts of the microscope - answer-
Condenser lens - answer-concentrates light and makes illumination of the species
more uniform
What produces a magnified real image? - answer-refraction of light as it passes
through the objective lens from the specimen
What happens at the ocular lens? - answer-image gets magnified again
What does the ocular lens produce? - answer-virtual image that appears below or
within the microscope
Total magnification of a microscope objective - answer-(magnification by objective
lens) x (magnification by ocular lens)
Magnification of ocular lens - answer-10x
What happens to image clarity as magnification increases? - answer-image clarity is
more difficult to maintain
Resolution - answer-clarity of an image
, Limit of resolution - answer-resolving power
Limit of resolution/resolving power - answer-actual measurement of how far apart
two points must be for the microscope to view them as being separate
What happens to resolution as the limit of resolution is made smaller? - answer-
resolution improves
Numerical aperture - answer-measure of a lens's ability to "capture" light coming
from the specimen and use it to make the image
What does immersion oil do to numerical aperture? - answer-increases numerical
aperture
What does immersion oil do to limit of resolution? - answer-makes limit of resolution
smaller
Dark field microscopy - answer-special condenser is used so only the light reflected
off the specimen enters the objective; brightly lit specimen in dark background;
better resolution
Phase contrast microscopy - answer-special optical components to exploit subtle
differences in the refractive indices of water and cytoplasmic components to produce
contrast
Fluorescence microscopy - answer-uses fluorescent dye that emits fluorescence
when illuminated with uv radiation
