Answer [2026] | UPDATED ACTUAL Exam | A+
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• objective lens . CORRECT ANSWER: closest to the specimen, forms initial
image called the real image
• ocular lens . CORRECT ANSWER: forms the second image called the virtual
image that will be received by the eye and converted to the retinal and visual image
• contrast (refractive index) . CORRECT ANSWER: measures the degree of
bending light as it passes from one medium to another.
• oil immersion lens . CORRECT ANSWER: uses oil to capture light that would
otherwise scatter. increases resolution, images must be 0.2 in diameter and 0.2 in
diameter apart
• wet mount . CORRECT ANSWER: consists of a drop or 2 of culture placed on a
slide and overlaid with a cover slip
• hanging drop . CORRECT ANSWER: drop of culture is placed on concave slide
with Vaseline adhesive or sealant, and cover slip are used to suspend the sample
• short term mounts . CORRECT ANSWER: provides true assessments of size,
shape, arrangement, color and motility.
• fixed stain smears . CORRECT ANSWER: more permanent used for long term
study, developed by Robert Koch. air dry, spread thin film made from liquid, heat
gently to kill specimen and attach to slide
,• stains . CORRECT ANSWER: procedure that applies colored chemicals (dyes)
to specimens.
• basic dyes . CORRECT ANSWER: have a positive charge
• acidic dyes . CORRECT ANSWER: have a negative charge. Acidic dyes are
repelled by cells.
• positive stains . CORRECT ANSWER: dye sticks to the specimen and gives it
color
• negative stains . CORRECT ANSWER: does not stick to specimen but settles
near its outer boundary forming a silhouette
• negatively charged cells . CORRECT ANSWER: repel the negatively charged
dye and remain unstained. smear is not heat fixed, used to accentuate a capsule,
nigrosin and india ink are used.
• simple stains . CORRECT ANSWER: requires a single dye and an
uncomplicated procedure. cells appear same color. used to reveal size, shape, and
arrangement.
• differential stains . CORRECT ANSWER: uses 2 different color dyes: primary
and counterstain. distinguishes cell types or parts, more complex and require more
chemical reagents to produce the desired reaction
, • gram stain . CORRECT ANSWER: developed in 1884 by Hans Christian Gram.
universal basis for bacterial classification and identification. aid in diagnosing
infection and guiding drug treatment
• acid fast stain . CORRECT ANSWER: acid fast bacteria (pink) from non acid
fast bacteria (blue). detects mycobacterium tuberculosis, these cell walls hold fast
to the dye when washed with an acid alcohol decolorizer. also used for bacteria,
fungi, and protozoa
• endospore stain . CORRECT ANSWER: similar to acid fast stain. stain
distinguishes between spores and vegetative cells. identifies gram positive, spore
forming members of the genus bacillus and clostridium
• capsule staining . CORRECT ANSWER: used to observe the microbial capsule,
a layer surrounding the cells of some bacteria and fungi. negatively stain with india
ink
• flagellar staining . CORRECT ANSWER: used to reveal tiny, slender filaments
used by bacteria for locomotion. flagella are enlarged by depositing a coating on
the outside of the filament and then staining it.
• The 5 I's of of Microbiology . CORRECT ANSWER: Inoculation, Incubation,
Isolation, Inspection, and Identification
• Inoculation . CORRECT ANSWER: implantation of microorganisms into or
onto culture media
• culture . CORRECT ANSWER: the reproduction of spreading microorganisms
with various media