International A Level Biology / Microbiology

Measuring growth: turbidity and mass

Edexcel International A Level Biology (YBI11), chapter 17: Microbiology, specification point 6.2. Part of the full course.

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Turbidity estimates the total number of cells from how cloudy a liquid culture is, while dry mass measures its biomass after the water is removed. Knowing what each method measures helps you choose the right way to measure microbial growth.

More lessons in Microbiology

• Bacteria and viruses compared
• Lytic and latent infections
• The bacterial growth curve
• Calculating exponential growth and the growth rate constant
• Culturing microorganisms with aseptic technique
• Measuring growth: cell counts and dilution plating
• Core practical 13: growth of microorganisms in liquid culture
• How pathogens enter and how the body keeps them out
• Tuberculosis: how Mycobacterium tuberculosis causes disease
• HIV: how the virus infects and leads to AIDS