Multiple Choice
Which of the following instruments and equipment must be sterilized before use in a microbiology laboratory?
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1. Introduction to Microbiology
Introduction to Microbiology
Multiple Choice
In the capsule stain using India ink, capsules are distinguished as __________ surrounding cells.
A
clear halos
B
darkly stained regions
C
pink cytoplasmic areas
D
blue granules
Verified step by step guidance1
Understand the principle of the capsule stain using India ink: India ink is an acidic stain that stains the background but does not penetrate the capsule or the cell.
Recognize that the capsule itself is a non-ionic, gelatinous layer that does not take up the stain, so it remains unstained or clear.
Note that the bacterial cell inside the capsule can be stained by a different stain (such as crystal violet or safranin), making it visible against the dark background.
Therefore, in the final microscopic image, the capsule appears as a clear, unstained halo surrounding the stained bacterial cell against the darkly stained background.
Conclude that the correct description of capsules in the India ink stain is 'clear halos' surrounding cells.
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