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WorksheetsGram Staining
Total questions: 85
Worksheet time: 53mins
Which of the following is the CORRECT order of the steps of a Gram stain?
Primary stain → Decolorizing agent → Mordant → Counterstain
Counterstain→ Mordant → Decolorizing agent→ Primary stain
Primary stain→ Mordant→ Decolorizing agent→ Counterstain
Primary stain→ Counterstain→ Decolorizing agent→ Mordant
Which part of the bacteria contains Peptidoglycan?
Lipoproteins
Cell wall
Cell membrane
Porin channel
Who first discovered the process of Gram Staining?
Charles Christian Gram
Hans Christian Ham
Gram Christian Han
Hans Christian Gram
Around what year was Gram staining discovered?
Early 1900s
Late 1900s
Late 1800s
Early 1800s
Which layer of the bacteria is dyed/stained purple?
Cell membrane
cell wall
capsule
slime layer
Gram-negative bacteria stain____. This is because the____is NOT retained after decolorization.
purple; safranin
purple; crystal violet
pink; safranin
pink; crystal viotel
Gram____bacteria have two membranes and____embedded in their outer-membrane that protects the cell and makes it more resistant to antibiotics.
negative; LPS
positive; SPS
positive; LPS
negative; LPS
The peptidoglycan cell wall in bacteria is made of these TWO elements.
proteins & carbohydrates
proteins & sugars
carbohydrates & fats
fats & sugars
Gram____bacteria have a thick layer of peptidoglycan in their cell wall.
positive
negative
These are the TWO sugars that make up the peptidoglycan layer.
NAS & LPS
NAG & NAS
NAM & NAG
LPS & NAM
In this step of the gram-staining procedure ____is used to decolorize the bacterial smear. This is the___step of the procedure.
iodine; 2
alcohol; 3
iodine; 1
alcohol; 4
_____traps crystal violet in the thick peptidoglycan layer of gram-positive bacterial cells.
alcohol
safranin
iodine
decolorizer
Safranin is the_______which means the bacterial will both be stained this color in the last step.
reverse stain
negative stain
counter stain
positive stain
Gram-staining is important because_____(choose ALL that apply)
it helps diagnose bacterial diseases
it allows physicians to determine the type of antibiotic to be used
it is used in food production to test safety
all of the above are correct
Gram-negative bacteria have cell walls with
A thick peptidoglycan layer and an outer membrane
A thin peptidoglycan layer and an outer membrane
A thin peptidoglycan layer and no outer membrane
A thick peptidoglycan layer
What is the correct order of staining reagents in Gram-Staining?
Crystal violet, alcohol, iodine solution, safranin
Crystal violet, iodine solution, alcohol, safranin
Crystal violet, safranin, alcohol, iodine solution
Iodine solution, crystal violet, alcohol, safranin
Which of the following is NOT true from gram negative bacteria
thin peptidoglycan wall
outer lipopolysaccharide membrane
becomes pink or red with gram staining
susceptible to antibiotics like penicillin
What chemical is used as the primary stain in a Gram stain?
crystal violet
iodine
alcohol
safranin
What chemical is used as the counterstain during Gram staining?
crystal violet
iodine
alcohol
safranin
What is Gram's Iodine used for during Gram staining?
primary stain
counterstain
fixative / mordant
decolorizer
What is the purpose of the alcohol during Gram staining?
to use as the primary stain
to use as the counterstain
to remove the primary stain from Gram - bacteria
to remove the primary stain fro Gram + bacteria
Which best describes the bacteria shown in the picture?
Gram - streptococcus
Gram - bacillus
Gram + streptococcus
Gram + bacillus
The E. Coli bacteria pictured can be classified as...
Gram + bacillus
Gram - bacillus
Gram + streptococcus
Gram - staphylococcus
Lipid contents are more in
Gram negative bacteria
Gram positive bacteria
Both
None of the above
Peptidoglycan accounts for __________ of the dry weight of cell wall in many gram positive bacteria.
less than 10%
10-20%
less than 50%
50-90%
Peptidoglycan accounts for __________ of the dry weight of cell wall in many gram negative bacteria.
less than 10%
10-20%
less than 50%
50-90%
Which of the following is false about the cell wall of Gram + bacteria?
It consists of multiple layers of peptidoglycan
It is thicker than Gram - layers
It is more resistant to antibiotics
It has less layers than Gram - cells
Peptidoglycan is found only in the bacterial __________________.
cell membrane
cell wall
endospore
glycocalyx
Which of the following statements is NOT correct about bacterial cells.
Gram positive are more sensitive to antibiotics because of the structure of their cell wall.
Gram negative bacteria do not have peptidoglycan in their cell walls.
The two dyes used to stain bacteria are crystal violet and safranin.
Hans Christian Gram was the scientist who discovered the Gram Staining process.
How would you describe Letter A?
Gram + coccus
Gram - coccus
Gram + bacillus
Gram - bacillus
Gram - spirillum
How would you describe Letter B?
Gram + coccus
Gram - coccus
Gram + bacillus
Gram - bacillus
Gram - spirillum
How would you describe Letter C?
Gram + coccus
Gram - coccus
Gram + bacillus
Gram - bacillus
Gram - spirillum
What bacteria from our lab could letter A represent?
Aquaspirillum itersonii
Bacillus cereus
Escherichia coli
Lactococcus lactis
Sporosarcina ureae
What bacteria from our lab could letter B represent?
Aquaspirillum itersonii
Bacillus cereus
Escherichia coli
Lactococcus lactis
Sporosarcina ureae
What bacteria from our lab could letter C represent?
Aquaspirillum itersonii
Bacillus cereus
Escherichia coli
Lactococcus lactis
Sporosarcina ureae
What color would Gram + and Gram - bacteria be after heat fixation.
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram positive bacterial cells be after crystal violet?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram positive bacterial cells be after iodine?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram positive bacterial cells be after alcohol?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram positive bacterial cells be after safranin?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram negative bacterial cells be after crystal violet?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram negative bacterial cells be after iodine?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram negative bacterial cells be after alcohol?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
What color would Gram negative bacterial cells be after safranin?
Blue/Purple
Pink/Red
No color (clear/transparent)
None of the above
Which cell type in the picture above is a Gram - cell?
Cell Type A
Cell Type B
Both
Neither
Which cell type in the picture above is a Gram + cell?
Cell Type A
Cell Type B
Both
Neither
What is the name of structure labeled “A” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “B” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “C” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “D” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “E” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “F” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “G” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
What is the name of structure labeled “H” in the above picture?
Cell wall
Peptidoglycan
Periplasmic space
Plasma membrane
Outer membrane
Peptidoglycan is an important molecule of bacterial cells walls. Which of the following statements regarding peptidoglycan and bacterial cells is NOT true?
Gram-negative bacteria have a periplasmic space between the cell wall and the cell membrane.
The outermost membrane of gram-negative bacteria contains the endotoxin lipopolysaccharide (LPS).
The peptidoglycan in the cell wall is the outermost layer of Gram-negative bacteria.
The peptidoglygan cell wall is thicker in Gram-positive bacteria.
In Gram Staining, this chemical is used to stain Gram positive cells.
Alcohol
Crystal violet
Iodine
Safranin
In Gram Staining, this chemical dehydrates the peptidoglycan layer in Gram positive and shrinks it so the primary stain gets trapped in the peptidoglycan.
Alcohol
Crystal violet
Iodine
Safranin
In Gram Staining, this chemical acts to bind the primary stain to the peptidoglycan in Gram positive cells.
Alcohol
Crystal violet
Iodine
Safranin
In Gram Staining, this chemical is called the counterstain.
Alcohol
Crystal violet
Iodine
Safranin
In Gram Staining, this chemical is called the decolorizer.
Alcohol
Crystal violet
Iodine
Safranin
Which chemical is used to stain Gram + cells?
Alcohol
Crystal violet
Iodine
Safranin
Which chemical is used to stain Gram - cells?
Alcohol
Crystal violet
Iodine
Safranin
How would you describe Letter A?
Gram + coccus
Gram - coccus
Gram + bacillus
Gram - bacillus
Gram - spirillum
How would you describe Letter B?
Gram + coccus
Gram - coccus
Gram + bacillus
Gram - bacillus
Gram - spirillum
What bacteria from our lab could letter A represent?
Aquaspirillum itersonii
Bacillus cereus
Escherichia coli
Lactococcus lactis
Sporosarcina ureae
What bacteria from our lab could letter B represent?
Aquaspirillum itersonii
Bacillus cereus
Escherichia coli
Lactococcus lactis
Sporosarcina ureae
The following do not Gram stain due to atypical cell walls except:
Leprosy
Spirochete bacteria
Staphylococcus bacteria
Tuberculosis
Which of the following statements is NOT true about gram negative bacteria?
Safranin is used as a counterstain
Contains an outer membrane
Contains a thick layer of peptidoglycan
Contains a periplasmic space
Peptidoglycan can be found in the _______________.
Cell envelope
Cell membrane
Cell wall
Outer membrane
The bacteria labeled A is called _________________.
Gram +
Gram -
The bacteria labeled B is called _________________.
Gram +
Gram -
In the illustration, the highest concentration of peptidoglycan will be found in cell ___.
A
B
Safranin is used as a counterstain to dye which bacteria?
A
B
Crystal violet is used to stain which bacteria?
A
B
E. coli contains endotoxins and therefore would have this cell wall structure.
A
B
This cell is more resistant to antibiotics and disinfectants due to the structure of its cell wall.
A
B
Which part of a Gram - cell contain the toxin which makes us sick?
Cell wall
Cell membrane
LPS
Periplasmic space
Which part of a Gram - cell degrades chemicals and antibiotics?
Cell wall
Cell membrane
LPS
Periplasmic space
Outer membrane
Which type of bacteria contains more than 1 layer of phospholipid bilayers?
Gram Negative
Gram Positive
Both (-) and (+)
Which type of bacteria contains 2 layers in the cell envelope?
Gram Negative
Gram Positive
Both (-) and (+)
Which type of bacteria contains 3 layers in the cell envelope?
Gram Negative
Gram Positive
Both (-) and (+)
If the iodine step were omitted in the Gram-staining procedure, what color would you expect Gram positive bacteria to stain and what color would you expect Gram negative bacteria to stain?
Gram positive = purple; Gram negative = red
Gram positive = purple; Gram negative = purple
Gram positive = purple; Gram negative = colorless
Gram positive = red; Gram negative = purple
Gram positive = red; Gram negative = red
