Multiple Choice
Which of the following is necessary for a successful streak plate technique in microbiology?
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1. Introduction to Microbiology
Introduction to Microbiology
Multiple Choice
How does the agar concentration in media used for motility testing differ from that used for standard plate cultures?
A
Motility testing media does not contain any agar.
B
Both motility testing and plate culture media use the same agar concentration.
C
Motility testing media contains a lower concentration of agar to allow bacteria to move through it.
D
Motility testing media contains a higher concentration of agar to restrict bacterial movement.
Verified step by step guidance1
Understand the purpose of agar concentration in microbiological media: Agar is a solidifying agent that provides a semi-solid or solid surface for bacterial growth.
Recognize that standard plate cultures use a higher agar concentration (usually around 1.5%) to create a firm surface where bacteria grow as isolated colonies without movement through the medium.
Know that motility testing media requires a lower agar concentration (typically around 0.4%) to create a semi-solid medium that is soft enough to allow motile bacteria to move or swim through it.
Compare the agar concentrations: lower agar concentration in motility media facilitates bacterial movement, whereas higher agar concentration in standard plates restricts movement and supports colony formation.
Conclude that motility testing media contains a lower concentration of agar than standard plate cultures to allow bacteria to move through the medium, which is essential for observing motility.
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