Microbiology Lab Practical #1 Review-
Questions & Answers
Bacterial Smear Correct Ans-Allows better visualization of specimens using microscopy.
Heat Fixing Correct Ans-kills organisms, keeps organisms stuck to slide, allows the specimen
to be stained more easily
Aseptic Technique Correct Ans-preparing and handling sterile products in a manner that
prevents microbial contamination
Gram Staining Procedure Correct Ans-1. Heat fix bacterial smear
2. Cover with Crystal Violet (Primary Stain) and wait 60 seconds
3. Rinse slide with distilled water until stain is removed
4. Cover with Gram's Iodine (Mordant) and wait for 60 seconds
5. Rinse with distilled water
6. 2-3 drops of Decolorizer (95% Ethanol), or until color is clear, rinse with distilled water
7. Cover with Safranin (Counter Stain) and wait 45 seconds
8. Rinse with distilled water
9. Blot dry with Bibulous paper, observe under oil immersion and record results
Capsule Stain Procedure Correct Ans-1. Agitate broth culture
2. 2-3 loop fulls of broth culture added to slide and allow to air dry (NOT HEAT FIXING)
, 3. Cover with Crystal Violet (Primary Stain) and wait for 2 minutes
4. Rinse with 20% Copper Sulfate Solution (Decolorizer and counter stain)
5. DO NOT RINSE WITH WATER
6. Air dry for a few minutes and DO NOT BLOT
Observe under oil immersion and record results
Why do you not heat fix during the capsule stain procedure? Correct Ans-Heat will cause the
capsule to dislodge
Why do you not rinse with water during the capsule stain procedure? Correct Ans-Water will
remove the capsule from the cell
Why do you not blot during the capsule stain procedure? Correct Ans-Blotting will remove
the bacteria from the slide and/or distort the capsule
Which staining procedure will have purple cells surrounded by a clear or faint blue halo on a
purple background? Correct Ans-Capsule Staining Procedure
The halo is the capsule
Which staining procedure will have small purple cocci (spheres)? Correct Ans-Gram staining,
purple is gram positive
Which staining procedure will have large purple rods? Correct Ans-Gram staining, purple is
gram positive
Questions & Answers
Bacterial Smear Correct Ans-Allows better visualization of specimens using microscopy.
Heat Fixing Correct Ans-kills organisms, keeps organisms stuck to slide, allows the specimen
to be stained more easily
Aseptic Technique Correct Ans-preparing and handling sterile products in a manner that
prevents microbial contamination
Gram Staining Procedure Correct Ans-1. Heat fix bacterial smear
2. Cover with Crystal Violet (Primary Stain) and wait 60 seconds
3. Rinse slide with distilled water until stain is removed
4. Cover with Gram's Iodine (Mordant) and wait for 60 seconds
5. Rinse with distilled water
6. 2-3 drops of Decolorizer (95% Ethanol), or until color is clear, rinse with distilled water
7. Cover with Safranin (Counter Stain) and wait 45 seconds
8. Rinse with distilled water
9. Blot dry with Bibulous paper, observe under oil immersion and record results
Capsule Stain Procedure Correct Ans-1. Agitate broth culture
2. 2-3 loop fulls of broth culture added to slide and allow to air dry (NOT HEAT FIXING)
, 3. Cover with Crystal Violet (Primary Stain) and wait for 2 minutes
4. Rinse with 20% Copper Sulfate Solution (Decolorizer and counter stain)
5. DO NOT RINSE WITH WATER
6. Air dry for a few minutes and DO NOT BLOT
Observe under oil immersion and record results
Why do you not heat fix during the capsule stain procedure? Correct Ans-Heat will cause the
capsule to dislodge
Why do you not rinse with water during the capsule stain procedure? Correct Ans-Water will
remove the capsule from the cell
Why do you not blot during the capsule stain procedure? Correct Ans-Blotting will remove
the bacteria from the slide and/or distort the capsule
Which staining procedure will have purple cells surrounded by a clear or faint blue halo on a
purple background? Correct Ans-Capsule Staining Procedure
The halo is the capsule
Which staining procedure will have small purple cocci (spheres)? Correct Ans-Gram staining,
purple is gram positive
Which staining procedure will have large purple rods? Correct Ans-Gram staining, purple is
gram positive
