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Microbiology Lab Midterm- Staining Techniques
Question and answers already passed 2025
1.
-primary stain: crystal violet, applied for 1
minute, washed with tap water
-mordant: gram's iodine, applied for 1 minute,
washed
with tap water
-decolorizing agent: ethyl alcohol, applied drop
wise, washed with tap water
-counterstain: safranin, applied for 45 sec, washed
with
tap water
2.
-primary stain: carbol fuchsin, applied for 5 min
with heat, do not let stain evaporate, washed off
with tap water
-decolorizing agent: acid alcohol, added drop wise,
washed off with tap water
-counterstain: methylene blue, applied for 2
minutes,
washed off with tap water
3.
-primary stain: malachite green, applied over heat
-decolorizing agent: water
-counterstain: safranin, applied for 30 sec, washed
off
with tap water
4.
-primary stain: crystal violet
-spread to form a thin smear with a clean glass
slide, let stand 5-7 minutes, do not heat fix
-decolorizing agent: 20% copper sulfate
5. -
primary
stain:
nigrosin
-spread
to form
a thin
smear
with a
clean
glass
slide,
let
stand
5-7
minute
s, do
not
heat fix
