Which of these methods can be used to determine the number of viable microorganisms in a sample?

Question

Quizplus · Accepted Answer

The method of measuring colony forming units per ml involves plating a sample onto an appropriate growth medium and counting the number of visible colonies that result. This provides an estimate of the number of viable microorganisms in the sample. The other methods listed do not specifically differentiate between viable and non-viable microorganisms. A spectrophotometer can measure the turbidity of a culture, but this only provides an estimate of total cell mass and cannot differentiate between live and dead cells. Counting a known volume of cells in a hemocytometer also does not specifically distinguish between live and dead cells.

Which of These Methods Can Be Used to Determine the Number