Microbiology Lab Practical #1(Georgia
Southern University Spring 2025) Qs & As
Why is boiling water used as the mordant for an endospore stain? Correct Ans-1. Boiling
water acts as the mordant and breaks down the spores, allowing them to absorb the malachite
green
2. Because the spores are so heat resistant, boiling water for at least 5-6 minutes is necessary to
allow the stain to enter into the spore
Example of a spore-forming bacterium Correct Ans-Bacillus subtilis or B. megaterium
Colors of vegetative cells and spores after staining Correct Ans-1. Vegetative cells are pink
2. Spores are green
Example of acid-fast organisms Correct Ans-1. Mycobacterium tuberculosis and M. leprae:
pathogenic
2. M. smegmatis: not pathogenic
boiling water as the mordant for an acid fast stain Correct Ans-calbolfuchsin and heat allow
the calbolfuchsin to penetrate into the lipid cell wall to stain the entire cell
Carbolfuchsin Correct Ans-Primary stain of acid fast stain
,heat/steam Correct Ans-Mordant of acid fast stain
acid alcohol Correct Ans-Decolorizing agent of acid fast stain
methylene blue Correct Ans-Secondary stain of acid fast stain
Appearance under the microscope of an acid fast stain Correct Ans-1. Blue: non acid fast
2. Red/pink: acid fast
Microscope: cleaning the lens Correct Ans-1. lens tissue on the actual lens
2. Kim's wipes to wipe slide
air contamination on agar plate Correct Ans-1. to prevent exposure to air contamination cover
of plate should always be left closed
2. when organisms are removed from a plate culture the cover should be only partially opened
1. upside down so that condensation doesn't drip on the sample
2. This prevents moisture from condensing on the agar surface and spreading the inoculated
organism Correct Ans-How should agar plates be incubated? Why?
BSL 1 Correct Ans-no disease/sink required
, BSL 2 Correct Ans-disease/lab coat& gloves
BSL 3 Correct Ans-Serious/lethal , decontaminate laundry, respiratory protection
BSL 4 Correct Ans-Life-threatening /shower required
Protozoa Correct Ans-Nucleus:+
Flagella:+/-
Pseudopodia:+/-
Cilia:+
Photosynthetic pigments: -
Chloroplasts: -
Cell wall: -
Algae Correct Ans-Nucleus:+
Flagella:+/-
Pseudopodia:-
Cilia:+/-
Photosynthetic Pigments:+
Chloroplasts:+
Cell wall:+
Southern University Spring 2025) Qs & As
Why is boiling water used as the mordant for an endospore stain? Correct Ans-1. Boiling
water acts as the mordant and breaks down the spores, allowing them to absorb the malachite
green
2. Because the spores are so heat resistant, boiling water for at least 5-6 minutes is necessary to
allow the stain to enter into the spore
Example of a spore-forming bacterium Correct Ans-Bacillus subtilis or B. megaterium
Colors of vegetative cells and spores after staining Correct Ans-1. Vegetative cells are pink
2. Spores are green
Example of acid-fast organisms Correct Ans-1. Mycobacterium tuberculosis and M. leprae:
pathogenic
2. M. smegmatis: not pathogenic
boiling water as the mordant for an acid fast stain Correct Ans-calbolfuchsin and heat allow
the calbolfuchsin to penetrate into the lipid cell wall to stain the entire cell
Carbolfuchsin Correct Ans-Primary stain of acid fast stain
,heat/steam Correct Ans-Mordant of acid fast stain
acid alcohol Correct Ans-Decolorizing agent of acid fast stain
methylene blue Correct Ans-Secondary stain of acid fast stain
Appearance under the microscope of an acid fast stain Correct Ans-1. Blue: non acid fast
2. Red/pink: acid fast
Microscope: cleaning the lens Correct Ans-1. lens tissue on the actual lens
2. Kim's wipes to wipe slide
air contamination on agar plate Correct Ans-1. to prevent exposure to air contamination cover
of plate should always be left closed
2. when organisms are removed from a plate culture the cover should be only partially opened
1. upside down so that condensation doesn't drip on the sample
2. This prevents moisture from condensing on the agar surface and spreading the inoculated
organism Correct Ans-How should agar plates be incubated? Why?
BSL 1 Correct Ans-no disease/sink required
, BSL 2 Correct Ans-disease/lab coat& gloves
BSL 3 Correct Ans-Serious/lethal , decontaminate laundry, respiratory protection
BSL 4 Correct Ans-Life-threatening /shower required
Protozoa Correct Ans-Nucleus:+
Flagella:+/-
Pseudopodia:+/-
Cilia:+
Photosynthetic pigments: -
Chloroplasts: -
Cell wall: -
Algae Correct Ans-Nucleus:+
Flagella:+/-
Pseudopodia:-
Cilia:+/-
Photosynthetic Pigments:+
Chloroplasts:+
Cell wall:+
