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Biology LibreTexts

3.5: Review Questions

  • Page ID
    15968
  • 1. Explain the major differences between the gram positive and gram negative cell wall.

    2. Salmonella typhi is a gram negative organism.

    a. What color will it appear when simple stained with crystal violet?

    b. What color would it be if it was gram stained correctly?

    3. Explain how bacterial cells would look in the gram staining procedure if the following mistakes were made:

    a. Decolorizer left on too long

    b. Decolorizer not left on long enough

    c. Slide not heat-fixed before staining

    4. What is the difference between a simple stain and a differential stain?

    5. Explain why it is important to use only a small amount of bacteria when preparing a smear.

    6. What are the two things that are stained in a capsule stain? What is NOT stained in a capsule stain?

    7. Why would a health care provider be interested in knowing the gram reaction of a pathogenic bacterium?