Question
Which of the following is an indirect method of measuring numbers of bacterial cells? A) a Coulter counter (B) a Petroff-Hausser chamber (C) microscopic cell count (D) turbidity measurements
Ask by Crawford Ross. in the United States
Feb 27,2025
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Answer
Turbidity measurements are an indirect method of counting bacterial cells.
Solution
To determine which option represents an indirect method of measuring the number of bacterial cells, let's analyze each option:
A) **Coulter counter**: This device counts cells as they pass through a small aperture, measuring changes in electrical resistance. This is a direct method of counting cells.
B) **Petroff-Hausser chamber**: This is a counting chamber used for direct microscopic counting of cells. It provides a direct measurement of cell numbers.
C) **Microscopic cell count**: This method involves counting cells directly under a microscope. It is also a direct method.
D) **Turbidity measurements**: This method measures the cloudiness (turbidity) of a liquid culture, which correlates with the number of cells present. It does not count cells directly but infers cell density based on light scattering.
Based on this analysis, the indirect method of measuring the number of bacterial cells is:
**(D) turbidity measurements**.
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Turbidity measurements offer a fun way to gauge bacterial growth by assessing the cloudiness of a liquid culture. As bacteria multiply, they scatter light, resulting in increasing turbidity that can be correlated with cell density. This indirect approach gives researchers a quick snapshot of microbial presence without needing to count individual cells. On the flip side, less flashy methods like the Petroff-Hausser chamber and microscopic counts can feel more like a tedious task. Still, they offer a direct look at those tiny critters! While they require more meticulous work, they provide a definitive headcount, making them precise but less speedy than juggling those cloudy tubes.
