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Gram Stain

View the animation below, then complete the quiz to test your knowledge of the concept.

1The proper sequence of reagents in the Gram stain procedure is
A)iodine, ethanol, safranin, crystal violet.
B)safranin, crystal violet, ethanol, iodine.
C)crystal violet, ethanol, iodine, safranin.
D)crystal violet, iodine, ethanol, safranin.
E)ethanol, iodine, crystal violet, safranin.

2After performing a Gram stain of a mixed culture of gram positive and gram negative cells, you shout: “Oops, I forgot the iodine step!” What would you expect to see if you observed the slide under the microscope?
A)Purple gram positive and pink gram negative cells
B)Pink gram positive and purple gram negative cells
C)Colorless gram positive and pink gram negative cells
D)Pink gram positive and pink gram negative cells
E)Colorless gram positive and colorless gram negative cells

3The Gram stain of a bacterial cell is based on the chemical properties of its
A)cell membrane.
B)cell wall.

4Acetone can be used as the decolorizer in the Gram stain procedure.

5The Gram stain can only be performed on cultures grown in liquid media.

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