MICRO 3201 Final Lab Exam Auburn University

Where do you dispose of gloves?

Biohazard

Where do you dispose of slides

Sharps container

Where do you dispose of swabs?

Sharps container

Where do you dispose of tubes?

Discard cart

Where do you dispose of plates?

Biohazard

T/F: It is okay to wear open-toed shoes in lab.

False

T/F: It is okay to tie up long hair when entering lab.

True

Which BioSafety Level consists of indigenous or exotic microorganisms that can lead to disease of varying severity in healthy adults?

BSL 2

Which BSL consists of microorganisms that are not known to cause disease in healthy adults?

BSL 1

Which BSL consists of microorganisms that are dangerous and exotic with a high risk of aerosol transmitted infections? For these, there is rarely treatment/vaccines available, and infections are frequently fatal.

BSL 4

What BSL level requires a negative air flow?

BSL 3 & 4

What BSL level requires both negative air flow and a suit?

BSL 4

What BSL level consists of indigenous or exotic microorganisms that cause serious or potentially lethal disease through respiratory transmission?

BSL 3

What term means that microorganisms are everywhere?

Ubiquity

What technique is used in order to prevent contamination from microorganisms?

Aseptic Technique

What type of cleaning agent can destroy vegetative cells and viruses but does not destroy endospores?

Disinfectants

Which disinfectant have you used throughout the semester in this lab?

Lysol

After flaming your loop, how long should you wait before using the loop for it to cool down?

15-20 seconds

T/F: When opening a broth tube, you only need to flame the mouth of the tube once in order to prevent contamination.

False, you need to flame after removing cap and before replacing cap.

T/F: Label petri dish on agar side of plate.

True

Which microscope uses contrast created by a bright specimen with a dark background to view a specimen?

Dark Field [dark background with contrast]

Which microscope requires the use of stain and light is either passed through or reflected off of a specimen?

Bright-Field [use of stain]

Which microscope have you used this semester?

Bright-Field

Which microscope uses high intensity illumination to excite fluorescent molecules in the specimen?

Fluorescent

Which microscope converts the difference in optical density of cells into different shades of brightness/contrast?

Phase Contrast [optical density]

What are fluorophores?

Fluorescent particles in microbial cell

Which microscope structure is composed of the arm and the base?

Framework

Which microscope structure is a horizontal area that supports the microscope slide?

Stage

Which microscope structure consists of the eyepieces that typically provide a magnification of 10x?

Oculars

What structure on the microscope allows for the holding and moving of the slide around the stage?

Stage Clips

Which microscope structure collects and directs the light from the light source to the slide and is located under the area that supports the slide?

Condenser

What is the name of the microscope structures attached to a rotating nose-piece and have powers of 10x, 40x, and 100x?

Objectives

What objective lens is used with the immersion oil?

100x

How do you calculate total magnification?

ocular lens x objective lens

What is the immersion oil used for?

To bridge the gap between lens and slide

Which microscope structure controls the amount of light that reaches the slide?

Diaphragm

Which microscope structure is used to bring objects on the slide into initial focus?

Coarse Focus Knob

After moving to the 40x and 100x objective lenses, which microscope structure is used to bring your slide specimen into focus?

Fine Focus Knob

What is the term used to describe the distance between the bottom of the objective lens and the slide?

Working Distance

What term is used to describe the ability of a microscope to remain relatively in focus when changing from a lower power objective to a higher power objective?

Parfocal

Resolving Power

The ability of a lens system to show two closely spaced objects as distinct and separate.

numerical apperature

the mathematical expression that describes how the condenser lens concentrates and focuses the light rays away from the light source

What is lens paper used for?

cleaning the microscope lenses and objectives

What is the first step of performing any staining procedure?

Smear prep

What does heat fixing do?

Melts the cell wall in order for your specimen to stick to the slide - adheres it to slide

How do you heat fix a slide?

Pass ABOVE flame once or twice quickly

Which staining procedure is commonly used to visualize morphology and cell arrangement?

Simple Stain

What is methylene blue used for?

It is the stain used for simple stain procedures

What is the primary stain of Gram staining?

crystal violet

What is the secondary stain of Gram staining?

safranin

What is used as the mordant in a Gram stain?

Iodine

What is the decolorizer in Gram staining?

95% ethanol

List the correct order of use of stains for Gram staining

1. Crystal violent

2. Gram's iodine

3. Decolorizer

4. Safranin

What color does gram positive stain?

purple

What color does gram negative stain?

pink

Selective Media

favor the growth of one organism over another

Differential Media

allows growth of several types of microbes and displays visible differences among those microbes

What selective agent is in MSA that selects for sodium tolerant organisms?

Sodium Chloride

Is an MSA plate selective or differential?

Selective (only grows sodium tolerant microbes)

What is fermented by organisms such as Staphylococcus aureus on MSA to produce acid? Also what happens (color wise) to the plate?

Mannitol; it turns yellow

What type of media is Sheep's Blood Agar (SBA)?

Differential media

What type of hemolysis occurs when there is partial breakdown of RBCs producing a greenish discoloration around the colonies?

Alpha Hemolysis

What type of hemolysis occurs when there is complete breakdown of RBCs producing clear zones around the colonies?

Beta Hemolysis

What type of hemolysis occurs when there is no breakdown of RBCs and no effect of coloration?

Gamma Hemolysis

Which test determines if an organism produces the enzyme that degrades hydrogen peroxide into water and oxygen?

Catalase test (enzyme is called catalase)

If an organism can breakdown carbohydrates, what does this organism produce during the process?

Acid

In Phenol Red (PR) Carbohydrate tubes, the red coloration you originally began with turns what color when acid is produced?

Yellow

What do starch agar plates contain?

Starch

In a starch agar plate, what does amylase from the microbe hydrolyze?

Starch

What reagent is used for detecting the starch hydrolysis on a starch agar plate?

Iodine

T/F: Iodine is added before incubation of a starch agar plate.

False, added after

T/F: Bile esculin slants are both a selective and differential medium.

True

What color does a bile esculin slant become if the organism was able to hydrolyze esculin into esculetin?

Black (more than half the slant to be positive)

What color is a positive result for a bile esculin slant?

Black

What ingredient do coagulase tubes contain that allow for the possibility of an organism to coagulate?

Rabbit Blood Plasma

Which organism is a coagulase test often used to identify/confirm?

Staphylococcus aureus

When performing a KOH test, what is released from the cell in order to produce strings?

DNA

If an organism has a negative KOH test result (no strings present), what is the organism's Gram stain reaction?

Gram positive

If an organism has a positive KOH test result (strings present), what is the organism's Gram stain reaction?

Gram negative

What type of medium is an Eosin Methylene Blue (EMB) plate?

selective (because of the dye) and differential (degrees of lactose fermentation)

What is fermented on an EMB plate in order to produce acid?

Lactose

Which organism used in this course is characteristic of a green sheen production on an EMB plate?

E. coli

T/F: EMB plates select for gram positive organisms.

False, Gram Negative

O/F Glucose Test, What are we testing for?

Oxidation (respiration) and Fermentation

O/F Glucose test: what reagent is added to the top of the F tube in order to create an anaerobic environment?

Sterile Mineral Oil

What color does the O/F Glucose medium turn when a positive result is produced?

Yellow

What reagents are used in a Voges-Proskauer (VP) test?

VP1 (alpha-naphthol) and VP2 (KOH)

What color is a positive Citrate test?

Blue

Nitrate test: If the tube turns red after the addition of Nitrate A and Nitrate B, what does this mean?

Positive result - Nitrate was reduced to Nitrite

Nitrate test: If the tube did not turn red after Nitrate A and Nitrate B were added, but it does turn red are Zinc is added, what does this mean?

Negative result - Nitrate was not reduced

Nitrate test: if the tube does not turn red after the addition of Nitrate A, Nitrate B, or Zinc, what does this mean?

Positive result - Ammonia or another non-gaseous product was produced

What 3 tests does a SIM tube test for?

Hydrogen Sulfide, Indole, Motility

What is the color of a positive Hydrogen Sulfide (H2S) test?

Black

What is the reagent used to test for Indole production in a SIM tube?

Kovac's reagent

What color does the tube turn if indole is detected in a SIM test?

Red

Turbid

cloudy

What is the major organelle that bacteria use for motility?

Flagella

Chemotaxis

process of bacterial movement

What color is a negative Urea test?

Yellow-ish Orange

What color is a positive Urea test?

Pink