PORTAGE LEARNING: MICROBIOLOGY, MODULE 3 EXAM QUESTIONS WITH COMPLETE SOLUTIONS VERIFIED GRADED A+
micrometer
one millionth of a meter
nanometer
one billionth of a meter
two critical factors that influence our ability to see an object
resolution and contrast
resolution
the distance betwee...
micrometer
one millionth of a meter
nanometer
one billionth of a meter
two critical factors that influence our ability to see an object
resolution and contrast
resolution
the distance between two objects at which the objects still can be seen as separate
contrast
the difference in light absorbance between two (objects)
the closer two objects are to each other the __________________ the resolution
requirement
greater
the ________________ the contrast between an object and its background, the
harder it will be to see the object
lower
bright field microscope
simplest form of light, or optical, microscopy/light, most often emitted from a standard
halogen bulb, enters the microscope from the base (bottom) and is reflected via mirrors
towards the sample
before the light reaches the sample, it first passes through a ________________
converging the light beams into a focused area on the sample
condenser
, iris diaphragm
controls the amount of light that passes through the sample and into the objective lens
objective lens
the lens closest to the sample and yields the greatest amount of magnification
the degree of magnification is ______________________ to the amount of light
needed/to image samples clearly at higher magnifications, more light is required
directly proportional
ocular lens
eyepiece
10x
most common power of ocular lens
total magnification
objective x ocular lens=
staining
required due to the limitation of resolution on unstained cells, (i.e.) often the flat and
transparent regions of a cell may appear invisible under bright field conditions/with
various dyes, these regions can become labeled and thus visualized.
phase contrast microscope
able to visualize certain structures that would otherwise be invisible/ can provide
detailed images of live cells without staining./uses specialized condensers and
objectives, it amplifies the slight differences between cells and the surrounding medium
(background) to make the cells highly distinguishable/can be used to visualize cell
movements
dark field microscope
can be used to greatly increase the contrast between a specimen and background,
resulting in a dark background with bright objects in it/reflects light off of the specimen at
an angle/does not permit the visualization of intracellular structures
fluorescence microscope
takes advantage of fluorescent molecules called fluorophores to visualize cells on a
dark background/ energy of the incoming light is in the form of the ultraviolet (UV)
spectrum.
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