Question

multiple choice question
when a culture shows two or more microbes of uncertain identity that have been introduced into it, the culture is considered to be ______

• contaminated
• axenic/pure
• mixed

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Explanation:

To solve this, we analyze each option:

• "aseptic/pure" cultures have only one type of microbe, so this is incorrect.
• "mixed" cultures have multiple microbes, but when the additional microbes are unwanted (introduced and of uncertain identity), the term is "contaminated". A "mixed" culture can be intentional (with known microbes), but here the microbes are introduced and uncertain, so it's contamination.
• "contaminated" fits as it refers to a culture with unwanted, introduced microbes of uncertain identity.

Answer:

A. contaminated