question
When should you disinfect your lab bench?
answer
Before and after the lab session
question
Where do used test tubes go?
answer
Discard cart
question
Where do used petri plates go?
answer
Biohazard can
question
Where do used microscope slides go?
answer
Sharps container
question
BSL 1
answer
Microorganisms not known to cause disease in healthy adults
question
BSL 2
answer
Indigenous microorganisms that can lead to diseases of varying severity in healthy adults
question
BSL 3
answer
Indigenous or exotic microorganisms that cause serious or potentially lethal disease through respiratory transmission
question
BSL 4
answer
Microorganisms that are dangerous and exotic with high risk of aerosol transmitted infections
question
Define microorganism
answer
Living organisms that cannot be seen without a microscope
question
What does ubiquity mean?
answer
Microorganisms can be found everywhere
question
What do disinfectants do?
answer
Destroy vegetative cells and viruses but may not destroy endospores - cannot be used to sterilize surfaces
question
What's an example of a disinfectant?
answer
Lysol
question
How long should you let your loop cool after flaming it?
answer
15-20 seconds
question
Using asceptic technique, how should you open a test tube?
answer
While holding the sterilized loop in your dominant hand, use your dominant pinky finger to remove the cap of the tube.
question
After opening and before closing a test tube, what should you do?
answer
Flame the mouth of the tube to kill any bacteria or fungi
question
Brightfield microscopes
answer
Simplest form of microscopy where light is either passed through, or reflected off, a specimen.
question
Does Brightfield microscopy require the use of stains?
answer
Yes
question
Phase contrast microscopes
answer
Converts the differences in optical density of cells into different shades of brightness.
question
Do phase contrast microscopes require a stain?
answer
No
question
Darkfield microscopes
answer
Contrast is created by a bright specimen on a dark background
question
Do darkfield microscopes require a stain?
answer
No
question
Fluorescent microscopes
answer
Uses high intensity illumination to excite fluorescent molecules (fluorophores) in the sample.
question
What do fluorescent microscopes require the use of?
answer
Fluorophores
question
What parts of a brightfield microscope make up the frame?
answer
Arm and base
question
What is the horizontal area that supports the microscope slide called?
answer
Stage
question
What is the magnification of the ocular lens?
answer
10x
question
What are the three most common objective lens magnifications on a brightfield microscope?
answer
10x, 40x, and 100x
question
Which magnification requires the use of immersion oil?
answer
100x
question
What does the condenser in a microscope do?
answer
Collects and directs the light from the light source to the slide; located under the stage
question
Does the condenser affect the magnification power of the microscope?
answer
No
question
What does the diaphragm control?
answer
The amount of light that reaches the slide
question
Which knob should be used when on 40x and 100x magnification?
answer
Only the fine focus knob
question
Parfocal
answer
The ability of a microscope to remain relatively in focus when changing from lower power objective to a higher power objective
question
Numerical aperature
answer
A mathematical expression that describes how the condenser lens concentrates and focuses the light rays from the light source
question
Resolving power
answer
The ability of a lens system to show two closely spaced objects as distinct and separate
question
For a smear prep, does the bacteria sample go on the slide first, or the water droplet?
answer
Water droplet
question
For heat-fixing, how many times do you pass the slide above the Bunsen burner?
answer
3 times
question
What kind of stain is a gram stain?
answer
Differential stain
question
How old should bacterial cultures be for best staining results?
answer
18-24 hours
question
What color are gram positive bacteria after gram staining?
answer
Purple
question
What color are gram negative bacteria after gram staining?
answer
Pink
question
What is the primary stain in gram staining?
answer
Crystal violet
question
What is the mordant or sealant in gram staining?
answer
Gram's Iodine
question
What is the decolorizer in gram staining?
answer
Ethanol
question
Cocci
answer
Spheres
question
Bacilli
answer
Rods
question
What enzyme degrades hydrogen peroxide and avoids cellular damage as a result?
answer
Catalase
question
Which type of organisms produce catalase?
answer
Aerobes and facultative anaerobes
question
Do strict anaerobes produce catalase?
answer
No
question
Do aerotolerant bacteria produce catalase?
answer
No
question
Do facultative anaerobes grow by respiration or fermentation?
answer
Both
question
What indicates a positive catalase test?
answer
Bubbles
question
What indicates a negative catalase test?
answer
No bubbles
question
What does the oxidase assay test for?
answer
The presence of cytochrome oxidase (occurs in bacteria that carry out respiration where oxygen is the terminal electron acceptor)
question
What is the artificial electron acceptor used in oxidase testing?
answer
N,N,N',N'-tetramethyl-p-phenylenediamine
question
What indicates a positive oxidase test?
answer
Changes to blue coloring within 30 seconds
question
What indicates a negative oxidase test?
answer
Does not change to blue within 30 seconds
question
What does the KOH test look for?
answer
Gram negative or positive bacteria
question
What is a positive KOH test, and what does this mean?
answer
Strings present; this means the bacteria is gram negative
question
What is a negative KOH test, and what does this mean?
answer
No strings present; this means the bacteria is gram positive
question
Selective medium
answer
Media that only allows certain microorganisms to grow and inhibits the growth of others
question
Differential medium
answer
Media that can differentiate microorganisms based on a change in their appearance
question
What kind of medium is Mannitol Salt Agar?
answer
Selective and differential
question
What kind of medium is sheep blood agar?
answer
Differential
question
Beta hemolysis
answer
Complete lysis of red blood cells (clear zone around colonies)
question
Alpha hemolysis
answer
Incomplete lysis of red blood cells, producing a greenish discoloration around the colonies
question
Gamma hemolysis
answer
No hemolysis of red blood cells
question
What is usually produced if an organism can break down carbohydrates by oxidation or fermentation?
answer
Acid
question
What is amylose?
answer
A straight chain polymer of 200 to 300 glucose molecules
question
How is starch hydrolysis detected?
answer
Adding iodine to a colony growing on a starch agar plate
question
What do bacteria that hydrolyze starch produce?
answer
Amylases that degrade amylose and amylopectin
question
What kind of agar is used to identify organisms that hydrolyze esculin?
answer
Bile esculin agar
question
What kind of medium is bile esculin agar?
answer
Selective and differential
question
What is produced when an organism hydrolyzes esculin?
answer
Esculetin and dextrose
question
What is a positive test result on bile esculin agar?
answer
Medium turns black/dark brown entirely or more than 1/2 of the medium turns dark brown/black
question
What is the coagulase assay a good test for?
answer
Staphylococcus aureus
question
Are most strains of Staph. aureus coagulase positive or negative?
answer
Positive
question
What is used in a coagulase test?
answer
Blood plasma
question
What is a positive test result for the coagulase assay?
answer
Clotting
question
What is a negative test result for the coagulase assay?
answer
No clotting
question
What is a positive BHI test result?
answer
Growth/turbidity
question
What is a negative BHI test result?
answer
No growth (clear)
question
What color will colonies change on an MSA plate if they produce acid?
answer
Yellow
question
What color will colonies change on an MSA plate if they don't produce acid?
answer
They won't change color (stay red)
question
What does G(+)/A(+) mean?
answer
The organism in question is tolerant of salt (G+) and produces acid (A+).
question
What does G(+)/A(-) mean?
answer
The organism in question tolerates salt but does not produce acid.
question
What does G(-)/A(-) mean?
answer
The organism in question does not tolerate salt and also doesn't produce acid.
question
What is the process for a nitrate reduction?
answer
1. Add five drops of nitrate reagent A
2. Add five drops of nitrate reagent B
3. If tube does not exhibit a red coloration (positive test), add a small amount of zinc
4. If the tube changes to red after the addition of zinc, the organism tested negative; if the tube did not change colors even after the zinc addition, the organism test positive.
2. Add five drops of nitrate reagent B
3. If tube does not exhibit a red coloration (positive test), add a small amount of zinc
4. If the tube changes to red after the addition of zinc, the organism tested negative; if the tube did not change colors even after the zinc addition, the organism test positive.
question
What is a phenol red carb. tube positive test result?
answer
The tube exhibits a yellow color.
question
What is a phenol red carb. tube negative test result?
answer
The tube remains red
question
If an organism produces acid, what color should the phenol red tube change to?
answer
Yellow
question
What is a starch hydrolysis positive test result?
answer
Dark agar with a clear zone around streak line
question
What is a starch hydrolysis negative test result?
answer
Dark agar up to the streak line
question
What organisms is the BHI salt test good for?
answer
Steptococcus and Enterococcus
question
What organisms is the bile esulin hydrolysis test good for?
answer
Streptococcus and Enterococcus
question
What organisms is the SBA hemolysis test good for?
answer
Streptococcus and Bacillus
question
What organisms is the MSA test good for?
answer
Staphylococcus and Bacillus
question
What organisms is the nitrate reduction test good for?
answer
Staphylococcus, Bacillus, and Enterobacteriaceae
question
Which kind of test is good for all bacteria types?
answer
Phenol Red Carbohydrate Tubes
question
What organisms is the Starch hydrolysis test with iodine good for?
answer
Bacillus
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