Skip to main content
Back

Differential Staining quiz

Control buttons has been changed to "navigation" mode.
1/15
  • What is the main purpose of differential staining in microbiology?
    Differential staining is used to distinguish or differentiate different groups of bacteria using multiple dyes.
  • Name the two most common types of differential stains.
    The two most common differential stains are the Gram stain and the acid-fast stain.
  • On what basis does the Gram stain differentiate bacteria?
    The Gram stain differentiates bacteria based on differences in their cell wall composition.
  • What color do gram positive bacteria appear after Gram staining?
    Gram positive bacteria appear purple after Gram staining.
  • What color do gram negative bacteria appear after Gram staining?
    Gram negative bacteria appear pink after Gram staining.
  • Give an example of a gram negative bacterium.
    Escherichia coli is an example of a gram negative bacterium.
  • Give an example of a gram positive bacterium.
    Staphylococcus aureus is an example of a gram positive bacterium.
  • What is the main feature identified by the acid-fast stain?
    The acid-fast stain identifies bacteria with mycolic acid, a waxy material, in their cell walls.
  • Which bacterium is a classic example of an acid-fast organism?
    Mycobacterium tuberculosis is a classic example of an acid-fast bacterium.
  • What color do acid-fast bacteria appear after acid-fast staining?
    Acid-fast bacteria appear dark purple after acid-fast staining.
  • How do non-acid-fast bacteria appear after acid-fast staining?
    Non-acid-fast bacteria do not take on the dark purple color after acid-fast staining.
  • What is mycolic acid and why is it important in differential staining?
    Mycolic acid is a waxy material found in the cell walls of acid-fast bacteria, making them identifiable by the acid-fast stain.
  • Why are differential stains important in microbiology?
    Differential stains are important because they help group bacteria based on specific features, aiding in identification and classification.
  • What does the presence of a purple color in a Gram stain indicate about a bacterium?
    A purple color in a Gram stain indicates the bacterium is gram positive.
  • What does the presence of a pink color in a Gram stain indicate about a bacterium?
    A pink color in a Gram stain indicates the bacterium is gram negative.