Question

if safranin was omitted from the spore stain, the vegetative bacterial cells would appear ______ in color.

a. red
b. green
c. purple
d. clear (colorless)

this image shows the results of a spore stain performed on a known endospore-producing strain of bacteria. which statement below would correctly explain this image?

a. the water rinse steps washed out all dye in the spores.

Explanation:

Analyze the effect of omitting safranin

In the Schaeffer-Fulton endospore staining procedure, malachite green is the primary stain that colors endospores green, water is the decolorizer that washes the primary stain out of vegetative cells, and safranin is the counterstain that colors vegetative cells red/pink. If safranin is omitted, the decolorized vegetative cells remain colorless.

Analyze the provided microscopic image

The image shows only red/pink rod-shaped vegetative cells with no green endospores visible inside or outside the cells, despite the culture being a known endospore-producing strain. This indicates that the primary staining step with malachite green failed to stain the endospores, or the decolorization step washed it out of the spores (which can happen if heat was not applied during the primary staining step to force the dye into the spore coat).

Answer:

Question 1

• (A) Red
• (B) Green
• (C) Purple
• (D) Clear (colorless) (Correct answer)

Question 2

• (A) The slide was not heated with the primary stain, malachite green, so the endospores did not retain the dye. (Correct answer)