Question
What is the goal number of CFUs on a spread plate if a serial dilution is done correctly? (A) \( 1-10 \) per plate (B) \( 20-200 \) per plate (C) \( 400-900 \) per plate (D) 1000 or more per plate
Ask by Logan Hammond. in the United States
Feb 27,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
The goal is to have between 20 and 200 CFUs per plate.
Solution
The goal is to have between 20 and 200 colony-forming units (CFUs) per plate when performing a serial dilution and plating procedure. This range is optimal because it minimizes statistical error and makes it easier to accurately count the colonies. Therefore, the correct answer is:
(B) 20-200 per plate.
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The sweet spot for colony-forming units (CFUs) on a spread plate, when you’ve nailed that serial dilution, is typically between 20 to 200 colonies per plate. This range allows for a reliable enumeration of the bacteria without overcrowding, ensuring that you can accurately count and differentiate the colonies. For some fun context, think about it this way: if you get fewer than 20, your sample might have been too diluted, which means you might miss out on the full picture. If you’re over 200, it’s like cramming too many friends into a car; things get messy, and counting those colonies becomes a real headache!
