Negative stains such as eosin are also called _______.
a. capsule stains
b. endospore stains
c. simple stains
d. acid-fast stains

Verified step by step guidance

1. Understand the purpose of negative staining: Negative stains are used to stain the background instead of the microorganism, making the cells appear clear against a dark background.
2. Recall that eosin is an acidic dye, which carries a negative charge and does not penetrate the cell but stains the background.
3. Identify the term commonly used for stains that color the background rather than the cells themselves; these are known as acidic or negative stains.
4. Review the options given: capsule stains, endospore stains, simple stains, and acid-fast stains, and consider which category negative stains like eosin fall into.
5. Conclude that negative stains such as eosin are also called capsule stains because they are often used to visualize capsules by staining the background, leaving the capsule clear.

Key Concepts

Negative Staining

Negative staining is a technique where the background, rather than the microorganism, is stained. This creates a contrast that makes the cells appear clear against a dark background, useful for observing cell shape and size without heat-fixing.

Eosin as a Negative Stain

Eosin is an acidic dye that carries a negative charge, repelling the negatively charged bacterial cell surface. This property makes eosin suitable for negative staining, as it stains the background but not the cells themselves.

Types of Staining Techniques

Staining methods include simple stains (single dye), differential stains (distinguish cell types), and special stains like capsule, endospore, and acid-fast stains. Negative stains are a special category that highlight cells by staining the background.