#1
What is the primary purpose of Gram staining in microbiology?
To identify bacterial species
To determine bacterial motility
To differentiate bacteria based on cell wall composition
To assess bacterial metabolic activity
#2
Which color do Gram-positive bacteria appear after Gram staining?
#3
Which stain is used as the primary stain in the Gram staining technique?
Methylene blue
Safranin
Crystal violet
Carbolfuchsin
#4
What is the primary reason for Gram staining bacteria?
To determine bacterial shape
To assess bacterial viability
To differentiate between pathogenic and non-pathogenic bacteria
To classify bacteria based on cell wall characteristics
#5
Which step of the Gram staining process involves the application of a counterstain?
Primary staining
Mordant application
Decolorization
Counterstaining
#6
Which of the following is NOT a step in the Gram staining process?
Decolorization
Counterstaining
Fixation
Primary staining
#7
What component of bacterial cells determines whether they will appear Gram-positive or Gram-negative?
Cytoplasmic membrane
Cell wall composition
Ribosomes
Plasmids
#8
Who developed the Gram staining technique?
Robert Koch
Louis Pasteur
Hans Christian Gram
Joseph Lister
#9
Which type of bacteria retain the crystal violet stain in Gram staining?
Gram-positive
Gram-negative
Both Gram-positive and Gram-negative
Neither Gram-positive nor Gram-negative
#10
Which of the following is a characteristic feature of Gram-positive bacteria?
Thin peptidoglycan layer
Presence of an outer membrane
Stains pink after Gram staining
Retains crystal violet stain
#11
What is the purpose of the safranin stain in the Gram staining process?
To stain Gram-positive bacteria
To counterstain Gram-negative bacteria
To decolorize Gram-positive bacteria
To fix the crystal violet stain
#12
What color do Gram-negative bacteria appear after the counterstain in Gram staining?
#13
What is the function of the mordant in Gram staining?
To decolorize Gram-negative bacteria
To fix the crystal violet stain
To enhance the contrast of the stain
To neutralize the acid-fast bacteria
#14
Which step of the Gram staining process is most critical for differentiating between Gram-positive and Gram-negative bacteria?
Primary staining
Decolorization
Mordant application
Counterstaining
#15
Which component of Gram-negative bacteria is targeted by the decolorizing agent in Gram staining?
Lipopolysaccharide layer
Teichoic acids
Peptidoglycan layer
Flagella
#16
Which of the following bacterial species is known to be Gram-variable, meaning it may appear either Gram-positive or Gram-negative depending on growth conditions?
Escherichia coli
Staphylococcus aureus
Listeria monocytogenes
Clostridium perfringens
#17
What is the role of the iodine solution in the Gram staining process?
To fix the crystal violet stain
To decolorize Gram-negative bacteria
To enhance the contrast of the stain
To stabilize the cell wall