BIOS-242 Lab Practical Review
QUESTIONS AND VERIFIED
CORRECT ANSWERS
GRADED A+ [LATEST 2026-
2027] 100% GUARANTEED
PASS
______ _____/ ____ ______ _____- the organism is spread out on the plate to give lawn of
growth after incubation. Filter paper soaked in antibiotic solution is placed onto the plate prior
to incubation. During incubation the drug will diffuse out and , if it is effective, will give a clear
zone of where growth is prevented - CORRECT ANSWER-Kirby Bauer / disk diffusion test
______________- indicated the level of sensitivity or an organism to a drug - CORRECT
ANSWER-zone of inhibition
gram staining: steps 1-9 - CORRECT ANSWER-1) stain with crystal violet for 1 minute
2) wash off stain with tap water
3) stain with gram's iodine for 1 minute
4) wash off gram's iodine with tap water
5) add 95% alcohol drop by drop until alcohol runs almost clear
6) wash of 95% alcohol with tap water
, 7) counterstain with safranin for 45 seconds
8) wash off safranin with tap water
9) blot dry with bibulous paper
gram staining step 1: stain crystal violet for 1 minute:
what does this do? - CORRECT ANSWER-this stains all cells, both G+ and G-, PURPLE
gram staining step 5: add 95% alcohol drop by drop until alcohol runs almost clear:
what does this do? - CORRECT ANSWER-this process decolorized G- cells. The G+ cells remain
purple because the dye cannot leave through the thick layer of peptidoglycan
gram staining step 7: counterstain with safranin for 45 seconds:
what does this do? - CORRECT ANSWER-this stains the now colorless G- cells PINK
_____ ____ uses H2O2 to determine if the bacteria can use oxygen or not. If the test is positive
(produces bubbles) the organism is Staphylococci, if the test is negative (no bubbles) the
organisms is streptococci - CORRECT ANSWER-catalase test
catalase test- positive:
__________ and the organism is ___________ - CORRECT ANSWER-produces bubbles and
organism is staphylococci
catalase test- negative:
_________ and the organism is _________ - CORRECT ANSWER-no bubbles and the organism is
steptococci
QUESTIONS AND VERIFIED
CORRECT ANSWERS
GRADED A+ [LATEST 2026-
2027] 100% GUARANTEED
PASS
______ _____/ ____ ______ _____- the organism is spread out on the plate to give lawn of
growth after incubation. Filter paper soaked in antibiotic solution is placed onto the plate prior
to incubation. During incubation the drug will diffuse out and , if it is effective, will give a clear
zone of where growth is prevented - CORRECT ANSWER-Kirby Bauer / disk diffusion test
______________- indicated the level of sensitivity or an organism to a drug - CORRECT
ANSWER-zone of inhibition
gram staining: steps 1-9 - CORRECT ANSWER-1) stain with crystal violet for 1 minute
2) wash off stain with tap water
3) stain with gram's iodine for 1 minute
4) wash off gram's iodine with tap water
5) add 95% alcohol drop by drop until alcohol runs almost clear
6) wash of 95% alcohol with tap water
, 7) counterstain with safranin for 45 seconds
8) wash off safranin with tap water
9) blot dry with bibulous paper
gram staining step 1: stain crystal violet for 1 minute:
what does this do? - CORRECT ANSWER-this stains all cells, both G+ and G-, PURPLE
gram staining step 5: add 95% alcohol drop by drop until alcohol runs almost clear:
what does this do? - CORRECT ANSWER-this process decolorized G- cells. The G+ cells remain
purple because the dye cannot leave through the thick layer of peptidoglycan
gram staining step 7: counterstain with safranin for 45 seconds:
what does this do? - CORRECT ANSWER-this stains the now colorless G- cells PINK
_____ ____ uses H2O2 to determine if the bacteria can use oxygen or not. If the test is positive
(produces bubbles) the organism is Staphylococci, if the test is negative (no bubbles) the
organisms is streptococci - CORRECT ANSWER-catalase test
catalase test- positive:
__________ and the organism is ___________ - CORRECT ANSWER-produces bubbles and
organism is staphylococci
catalase test- negative:
_________ and the organism is _________ - CORRECT ANSWER-no bubbles and the organism is
steptococci
