Final answer:
There are different methods of cell counting, including direct and indirect methods. Turbidometry is an indirect method that measures the turbidity of a bacterial suspension to estimate cell density. It is different from direct methods of counting because it does not count individual cells, but instead uses a calibration curve.
Step-by-step explanation:
There are different methods of cell counting, including direct and indirect methods. The direct methods involve counting cells using a microscope or plating serial dilutions on agar.
The indirect methods, like turbidometry, measure the turbidity (cloudiness) of a bacterial suspension to estimate cell density. Turbidometry is different from direct methods because it does not count individual cells but instead correlates turbidity readings to cell density using a calibration curve.