(P) CB Lab L1-L2

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B

Which term refers to the collection of laboratory practices used to prevent contamination of microbial cultures, personnel, and the environment?

• a. Sterilization

• b. Aseptic technique

• c. Disinfection

• d. Sanitization

• e. Microbial control

C

What is the primary biological reason that aseptic technique is necessary in the laboratory?

• a. Microorganisms are fastidious

• b. Microorganisms are pathogenic

• c. Microorganisms are ubiquitous

• d. Microorganisms are microscopic

• e. Microorganisms are transparent

C

Which of the following is considered a primary goal of aseptic technique?

• a. Increasing the growth rate of bacteria

• b. Reducing the cost of laboratory materials

• c. Dual protection of the microorganism and the healthcare worker

• d. Enhancing the visibility of bacterial cells

• e. Identifying the genus and species of a specimen

E

What is the dedicated contamination-free work area established to protect sterile materials and cultures called?

• a. Biosafety Cabinet

• b. Clean room

• c. Aseptic perimeter

• d. Inoculation zone

• e. Sterile field

A

Which mechanism does flame sterilization use to induce microbial death?

• a. Protein denaturation

• b. DNA damage

• c. Cell wall lysis

• d. Lipid oxidation

• e. Osmotic shock

A

How long should an inoculating loop be heated in a Bunsen burner flame?

• a. 10-15 seconds

• b. 5 seconds

• c. 20-30 seconds

• d. Until it begins to smoke

• e. Exactly 60 seconds

C

What is the maximum time a cooled inoculating loop should sit idle before it is considered re-contaminated by ambient air?

• a. 10 seconds

• b. 15 seconds

• c. 20 seconds

• d. 30 seconds

• e. 60 seconds

D

Which instrument is specifically used for deep inoculation or creating stab cultures?

• a. Inoculating loop

• b. Pasteur pipette

• c. Cotton swab

• d. Inoculating needle

• e. Forceps

C

Which of the following should NEVER be flamed?

• a. Glass culture tubes

• b. Metal inoculating needles

• c. Plastic inoculating loops

• d. Mouths of Erlenmeyer flasks

• e. Metal inoculating loops

C

When handling broth cultures where cells have settled, what is the correct method to resuspend them?

• a. Shaking vigorously

• b. Vortexing for 1 minute

• c. Gently flicking the tube

• d. Inverting the tube 20 times

• e. Heating the tube slightly

D

Where should labels be placed on a Petri plate?

• a. On the lid

• b. On the side of the lid

• c. On the top center

• d. On the bottom (agar side)

• e. Labels are not necessary for Petri plates

D

During a tube-to-tube transfer, which finger should be used to remove the culture tube cap?

• a. Thumb

• b. Index finger

• c. Middle finger

• d. Little finger

• e. Ring finger

B

What technique involves picking up inoculum from the end of a previous quadrant to isolate colonies?

• a. Fishtail streak

• b. Quadrant streaking

• c. Lawn inoculation

• d. Spiral plating

• e. Deep agar stabbing

C

How should a Petri dish lid be held during inoculation to prevent airborne contamination?

• a. Completely removed and placed on the bench

• b. Held vertically next to the plate

• c. Lifted slightly at an angle to act as a shield

• d. Held upside down in the non-dominant hand

• e. It should not be opened at all

C

What is the correct pattern for inoculating an agar slant?

• a. Single straight line

• b. Three distinct dots

• c. Zigzag (fishtail) pattern

• d. Circular motion

• e. Stabbing the center

A

Which color biohazard bin is designated for solid agar cultures after they have been autoclaved?

• a. Yellow

• b. Blue

• c. Red

• d. Green

• e. White

D

Where should contaminated slides and disposable loops be disposed of?

• a. Regular trash bin

• b. Biohazard bag

• c. Yellow biohazard bin

• d. Biohazard sharps container

• e. Recyclable waste

C

What is the first action to take in the event of a biological spill?

• a. Pour disinfectant on the spill

• b. Cover the spill with paper towels

• c. Stay calm and inform the instructor immediately

• d. Run out of the laboratory

• e. Put on a second pair of gloves

C

What is the recommended concentration of sodium hypochlorite for cleaning biological spills?

• a. 1:1

• b. 1:5

• c. 1:10

• d. 1:50

• e. 1:100

D

How long should disinfectant remain in contact with a viscous biological spill?

• a. 5 minutes

• b. 10 minutes

• c. 15-20 minutes

• d. At least 30 minutes

• e. 60 minutes

C

Which of the following is a common aseptic mistake regarding culture caps?

• a. Flaming the cap

• b. Holding the cap with the little finger

• c. Placing the cap directly on the bench surface

• d. Keeping the cap on until the moment of transfer

• e. Labeling the side of the tube instead of the cap

B

In what direction should disinfectant be applied when cleaning a spill?

• a. From the center outward

• b. From the outside perimeter toward the center

• c. Top to bottom

• d. Left to right

• e. Randomly over the entire surface

A

Why should Petri plates be inverted during incubation?

• a. To prevent condensation from dripping onto the colonies

• b. To prevent the agar from drying out

• c. To encourage anaerobic growth

• d. To make them easier to stack

• e. To prevent the lid from falling off

A

Which principle of aseptic technique suggests treating all cultures as "potentially infectious"?

• a. Principle 1

• b. Principle 3

• c. Principle 5

• d. Principle 7

• e. Principle 10

C

What is the result of using an uncooled (hot) inoculating loop on a bacterial culture?

• a. It enhances the staining process

• b. It creates a pure culture

• c. It kills the bacterial cells

• d. It prevents aerosol formation

• e. It fixes the bacteria to the loop

B

Why are bacterial cells usually stained before microscopic examination?

• a. To make them grow faster

• b. Because they are naturally transparent/colorless

• c. To provide nutrients for the cells

• d. To protect the microscope lenses

• e. To prevent the cells from moving

C

Which type of dye carries a positively charged (+) chromogen?

• a. Acidic dyes

• b. Anionic dyes

• c. Basic dyes

• d. Neutral dyes

• e. Fluorescent dyes

A

Which bacterial structure does a basic dye typically bind to?

• a. Negatively charged peptidoglycan

• b. Positively charged proteins

• c. Hydrophobic lipids

• d. The glass slide surface

• e. Neutral polysaccharides

E

Which of the following is an example of an acidic (anionic) dye?

• a. Crystal Violet

• b. Methylene Blue

• c. Malachite Green

• d. Safranin

• e. Nigrosin

E

What staining technique colors the background while leaving the bacterial cells clear?

• a. Simple staining

• b. Differential staining

• c. Acid-fast staining

• d. Gram staining

• e. Negative staining

B

Which category of staining uses a single basic dye to determine morphology and arrangement?

• a. Special stain

• b. Simple stain

• c. Differential stain

• d. Structural stain

• e. Negative stain

E

What is the primary purpose of the "coiling" or "spiral" method when preparing a sputum smear?

• a. To concentrate the bacteria in the center

• b. To identify saliva content

• c. To kill the Mycobacterium species

• d. To prevent the smear from air drying

• e. To yield a uniform 2 x 3 cm smear

C

Which of the following is NOT an objective of heat fixation?

• a. Killing the microorganism

• b. Facilitating adhesion to the slide

• c. Increasing the size of the bacterial cell

• d. Rendering the cell wall porous

• e. Preserving the morphology of the cells

C

What occurs if a bacterial smear is too thick?

• a. The cells will wash off the slide

• b. The cells will appear transparent

• c. It causes cell clumping, making observation difficult

• d. The dye will not be able to penetrate the cells

• e. The heat fixation will fail

A

Who is credited with developing the Gram stain?

• a. Hans Christian Gram

• b. Louis Pasteur

• c. Robert Koch

• d. Joseph Lister

• e. Antonie van Leeuwenhoek

E

What is the primary stain used in the Gram staining procedure?

• a. Safranin

• b. Gram's Iodine

• c. Carbol Fuchsin

• d. Methylene Blue

• e. Crystal Violet

C

What is the function of Gram's Iodine in the Gram stain?

• a. Decolorizer

• b. Primary stain

• c. Mordant

• d. Counterstain

• e. Fixative

C

Which reagent in the Gram stain is considered the "critical step" for differentiation?

• a. Crystal Violet

• b. Gram's Iodine

• c. 95% Alcohol/Acetone

• d. Safranin

• e. Distilled water

D

What is the counterstain used in the Gram stain?

• a. Crystal Violet

• b. Methylene Blue

• c. Malachite Green

• d. Safranin

• e. Nigrosin

D

Gram-positive bacteria appear what color under the microscope?

• a. Pink

• b. Bright red

• c. Green

• d. Dark purple/violet

• e. Colorless

C

Why do Gram-negative bacteria turn pink/red?

• a. They have a thick peptidoglycan layer

• b. The CV-I complex is trapped in the cell wall

• c. Alcohol dissolves the lipid outer membrane, washing out the CV-I complex

• d. They do not have a cell wall

• e. They absorb the Iodine more than the Crystal Violet

E

Which organism is a representative example of a Gram-positive bacterium?

• a. Escherichia coli

• b. Klebsiella pneumoniae

• c. Pseudomonas aeruginosa

• d. Neisseria gonorrhoeae

• e. Staphylococcus aureus

D

Which of the following is a Gram-negative bacterium?

• a. Streptococcus pyogenes

• b. Enterococcus faecalis

• c. Bacillus cereus

• d. Escherichia coli

• e. Staphylococcus epidermidis

C

What is the typical duration for applying the decolorizer in a Gram stain?

• a. 1 minute

• b. 2 minutes

• c. 10-15 seconds

• d. 5-10 minutes

• e. 30 seconds

C

Acid-fast staining is primarily used to identify bacteria belonging to which genus?

• a. Staphylococcus

• b. Bacillus

• c. Mycobacterium

• d. Escherichia

• e. Neisseria

B

Which component of the cell wall makes certain bacteria "acid-fast"?

• a. Teichoic acid

• b. Mycolic acid

• c. Lipopolysaccharide

• d. Peptidoglycan

• e. Ergosterol

C

What is the primary stain used in the Ziehl-Neelsen method?

• a. Methylene Blue

• b. Crystal Violet

• c. Carbol Fuchsin

• d. Safranin

• e. Auramine

E

Which Acid-Fast staining method is known as the "Hot Method"?

• a. Kinyoun method

• b. Auramine-Phenol method

• c. Giemsa method

• d. Gram stain method

• e. Ziehl-Neelsen method

B

What is the decolorizer used in the Ziehl-Neelsen or Kinyoun methods?

• a. 95% Ethanol

• b. 3% Acid-Alcohol

• c. Distilled water

• d. Gram's Iodine

• e. Acetone

C

What color do Acid-Fast Bacilli (AFB) appear in a Ziehl-Neelsen stain?

• a. Blue

• b. Green

• c. Bright Red / Fuchsia

• d. Purple

• e. Yellow

B

What is the primary advantage of the Auramine-Phenol fluorescent method?

• a. It is cheaper than other methods

• b. It is used when bacteria are present in low quantities

• c. It does not require a microscope

• d. It can be used on any type of cell

• e. It uses heat to drive the stain

C

What is used as a "quenching counterstain" in the Auramine-Phenol method?

• a. Methylene Blue

• b. Brilliant Green

• c. Potassium Permanganate (KMnO4)

• d. Safranin

• e. India Ink

A

Under a fluorescence microscope, AFB appear as:

• a. Bright luminous yellow/green rods

• b. Blue rods

• c. Dark shadows

• d. Red rods

• e. Purple spheres

C

Which stain is the standard for detecting encapsulated yeast like Cryptococcus neoformans in CSF?

• a. Gram stain

• b. Acid-fast stain

• c. India Ink

• d. Acridine Orange

• e. Methylene Blue

E

Which fluorochrome stain binds to nucleic acids, showing DNA as green and RNA as orange?

• a. Methylene Blue

• b. Auramine-Phenol

• c. Crystal Violet

• d. Malachite Green

• e. Acridine Orange

C

Methylene Blue is specifically mentioned as a simple stain to observe which structures in Corynebacterium diphtheriae?

• a. Capsules

• b. Endospores

• c. Metachromatic granules

• d. Flagella

• e. Pili

D

Why must gloves always be worn when handling India Ink?

• a. It is highly toxic

• b. It is an acidic dye that stains skin easily

• c. It contains live bacteria

• d. It is a safety precaution

• e. It is radioactive

A

Which of the following is NOT a special stain?

• a. Gram stain

• b. Endospore stain

• c. Capsule stain

• d. Flagellar stain

• e. India Ink

B

What happens to the CV-I complex in Gram-positive cells during the alcohol step?

• a. It is washed out immediately

• b. It is dehydrated and trapped within the thick peptidoglycan

• c. It turns red

• d. It dissolves the cell wall

• e. It binds to the lipids

C

What should you do before attempting to clean up a biological spill?

• a. Pour bleach on it

• b. Pick up broken glass with your hands

• c. Inform the instructor/supervisor

• d. Open the windows

• e. Take a picture for documentation