microbiology lab questions

Which of the following stains require heat fixation?

Endospore Gram Simple Acid-fast

which of the following bacterial genera are capable of producing endospores?

clostridium bacillus

Which of the following provides a quick and effective method used to visualize and determine bacterial morphology and arrangement?

Simple stain

which of the following are diseases caused by an acid-fast bacterium?

TB Leprosy

if safranin was omitted from the endospore stain, what color would be the endospores appear?

green

in order to ensure that dye penetrates the spore coat and stains the endospore, which of the following is needed?

heat

When should heat fixation take place during the capsular stain?

heat fixation is not required in the capsular stain.

which of the following describes the correct sequence of the gram stain procedure?

heat-fixed slide; use of crystal violet, iodine, decolorizer, and safranin

which of the following describes the correct sequence of gram stain procedures

heat-fixed; use of crystal violet, iodine, decolorizer, and safranin

which stain is used to stain the background in the capsule stain?

india ink or nigrosin

the acid-fast cell wall contains large amounts of mycolic acid. this glycolipid ___

makes the cell wall resistant to decolorization with acid-alcohol also makes the cell wall less permeable to chemicals

--- is used to stain the endospore in the endospore staining procedure.

malachite green

the counterstain used in the acid-fast stain is ___ ___

methylene blue

a chemical that fixes dye in or on cells by forming an insoluble compounds is referred to as ---

mordant

which of the following is a significant lipid component of the cell walls of acid-fast bacteria?

mycolic acid

the acid-fast cell wall contains large amounts of mycolic acid. which of the following can be attributed to the presence of mycolic acid?

mycolic acid makes the cells more difficult to stain chemicals cannot readily penetrate the cell wall of these cells

the capsule staining technique begins with a ____ stain.

negative

Gram-___ cell walls contain a thin layer of peptidoglycan whereas gram-___ cells walls contain a thick layer of peptidoglycan.

negative, positive

If you decolorize for more than 30 seconds, gram-positive organisms will most likely appear ____ in color.

pink

if malachite green was omitted from the endospore stain, vegetative cells would appear ___ in color.

pink

if you omit the Gram's iodine step while preforming the Gram stain, gram-positive cells will most likely be ____ in color.

pink

if methylene blue was omitted from the acid-fast stain, what color would acid-fast cells appear?

pink/red

two clinically significant genera of bacteria that are capable of producing endospores are clostridum and bacillus.

True

you have just performed an acid-fast stain, and all of the cells appear to be blue. which of the following could explain you results?

the bacteria are non-acid fast.

encapsulated organisms are difficult to directly stain because ___

the capsule is not permeable to stains the capsule does not react with most stains

why is heat fixation not part of the protocol for the capsule stain?

the capsule may be damaged

Which of the following descriptions reflects observations of a capsular stain that may have been heat fixed?

the capsules cannot be seen clearly on the slide

which of the following structures makes it difficult to stain endopores

the endospore coat

what could happen if heat fixation was performed prior to doing a capsular stain?

the heat might alter the morphology of the bacteria.

what is stained by a counterstain in the acid-fast stain procedure?

the non-acid-fast organisms on the slide

you just preformed an acid-fast stain on an acid-fast organism, yet some of the bacteria appear blue and some appear red. which of the following could explain your result?

the primary stain was not allowed to stain long enough you have a mixed population of bacteria in which some organisms are acid-fast and some are not

you are observing Klebsiella pneumoniae on a slide that has been stained using the capsular staining method; however, you do not see capsules surrounding the cell as you expected. What is the likely reason for this?

the slide was heat fixed

what is thought to cause gram-positive cells to retain the primary stain and the mordant complex whereas gram-negative cells are decolorized?

the thickness of the peptidoglycan layer

what is thought to cause gram-positive cells to retain the primary stain and the mordent complex whereas gram-negative cells are decolorized?

the thickness of the peptidoglycan layer

which of the following apply to endospore?

they are used for surviving adverse environmental conditions

what is the purpose of a negative stain?

to visualize the bacteria to visualize the capsule to determine morphological structures of the specimen

an ___ is a metabolically active and growing cell

vegetative cell

there are many types of staining tech used in microbiology. which of the following is not a commonly used staining

wright's stain

Gram stain

a stain that can differentiate between cells that have thick or thin layers of peptidoglycan in their cell walls

Capsule stain

a stain that enables you to effectively visualize a bacterium's glycocalyx

Acid-Fast stain

a stain that would be appropriate for cells that contain mycolic acid in their cell walls.

which of the following are functions of the bacterial capsule?

adherence

place the steps of the endospore stain in the correct sequence?

apply malachite green to smear cover smear with small piece of paper towel steam over water bath rinse apply safranin to smear rinse and blot dry

why might it be important to perform a gram stain on bacterial cells?

as part of the information used to choose an appropriate antibiotic Tx

in a negative stain, which of the following is stained?

background

which of the following is stained during the first part of the capsule staining procedure?

background of the slide

which of the following is stained during the first part of the capsule staining procedure?

background on the slide

if carbolfuchsin was omitted from the acid-fast stain, what color would non-acid fast cells appear?

blue

which of the following stains do not require heat fixation?

capsule stain

--- is the initial stain used in the acid-fast stain

carbolfuchsin

in the Kinyoun acid-fast staining method, highly concentrated ___ is used to penetrate the cell wall and colorize acid-fast bacterial cells.

carbolfuchsin

if carbolfuchisin, was omitted from the acid-fast stain, what color would acid-fast cells appear?

clear

if malachite green was omitted from the endospore stain, the endospores would appear --- in color.

clear

The ___ stain provides critical information about peptidoglycan structure of the cell wall.

Gram

What is used as the mordant in the gram staining technique?

Gram's iodine

what might happen if you omitted the safranin step while performing the Gram stain on a mixed culture of gram positive and gram-negative cells?

Gram-negative organism might not be visible

What might happen if you omitted the safranin step while performing the Gram stain on the mixed culture of gram-positive and gram-negative cells?

Gram-negative organisms might not be visible

If you forget to use the decolorizer, which cell type(s) will appear purple?

Gram-positive and Gram-negative

What outcome could be expected if you forgot the crystal violet step while performing a Gram stain?

Gram-positive and gram-negative organisms would stain pink

if methylene blue was omitted from the acid-fast stain, NON-acid-fast cells would be ___ at the end of the staining process.

clear

if sarfranin was omitted from the endospore stain, the vegetative cells would appear --- in color.

clear

What is the primary dye used in the gram staining technique?

crystal violet

which stain is used to stain the cytoplasm of the cells in the capsule stain?

crystal violet

Place these reagents in the proper order of their use in the Gram staining techique

crystal violet gram's iodine decolorizer safranin

place these regents in the proper order of their use in the Gram staining technique

crystal violet gram's iodine decolorizer safranin

in a differential staining technique, a --- is used to remove the primary stain from bacterial cell.

decolorzier

in order to withstand hostile conditions and facilitate survival, some bacteria produce resistant structures known as

endospores

endospores are difficult to stain due to which of the following?

endospores have thick spore coat endospores exclude dye

omitting the steaming in an endospore stain would result in which of the following?

endospores would not take up stain

if decolorization was omitted from the acid-fast stain, what color would non acid-fast cells appear?

f carbolfuchipink/red

what is the primary due used in the gram staining technique?

gram's iodine

what type of cell wall contains a thick layer of peptidoglycan and no outer membrane?

gram-positive

if you forget to use the decolorizer, which cell type(s) will appear purple?

gram-positive gram-negative

which of the following correctly describe how the Gram stain works to color different types of cells?

gram-positive cells retain the purple dye-mordant complex because of their thick layer of peptidoglycan. gram-negative cells are decolorized and stained by the pink/red secondary stain

place the following steps of the capsular stain in the proper sequence?

place a drop of nigrosine on a clean slide add bacteria to nigrosine and mix spread the mixture over slide and air dry apply crystal violet rinse

which of the following are terms used to describe the colored dyes applied in the Gram staining technique?

primary and counterstain

which of the following are terms used to describe colored dyes applied in the Gram staining technique?

primary stain counterstain

if decolorization was omitted from the acid-fast stain, which color would acid-fast cells appear?

red

if you decolorize for more that 30 seconds, gram-positive organisms will most likely appear ___ in color

red

if you omit the Gram's iodine step while performing the Gram stain, gram-positive cells will most likely be --- in color.

red

Gram-negative cells appear ___ after Gram staining whereas gram-positive appear __

red purple

Gram-negative cells appear __ after Gram staining whereas gram-positive cells appear __.

red, purple

--- is used to stain the vegetative cells in the endospore staining procuder?

safranin

The name of the counterstain, or secondary stain, typically used in the gram stain technique is ___

safranin

the name of the counterstain, or secondary stain, typically used in the Gram stain technique is ___

safranin

which three of the following terms all refers to a similar structure?

slime layer capsule glycocalyx

place the flowing steps of the acid-fast stain in the proper sequence

stain with carbolofuchsin rinse off excess primary stain decolorize with acid-alcohol rinse with water to stop the decolorization process counterstain with methylene blue rinse off counterstain blot dry

which occurs first in the endospore stain?

staining of the endospore

In the capsular stain, what does the counterstain dye?

the background

what is stained by the initial dye in the capsular stain procedure?

the background

a capsule stain was performed, using crystal violet as a primary stain, followed by a water rinse, and then nigrosine as a counterstain. As you observe the slide through the microscope, you suspect you made an error. Which of the following is the most likely problem with you technique?

you should have started with nigrosine as t primary stain and used crystal violet as the counterstain