Chapter 5.9 Viable Counts

Question 1

What is a viable cell count, and what is another name for it?

Answer 1

It is a measurement of living, reproducing population.

It is also called Plate Counts

Question 2

What are the two main ways to perform plate counts?

Answer 2

1. ) Spread-Plate Method

2. ) Pour-Plate Method

Question 3

In order to obtain the appropriate colony number, what must always be done to the sample?

Answer 3

The sample must always be diluted

Figure 5.17

Question 4

Plate counts can be highly unreliable when used to assess total cell numbers of what type of samples?

Give examples of samples.

Answer 4

Natural samples

Examples: Soil and Water

Question 5

Selective culture media and growth conditions target what?

Answer 5

Only particular species

Question 6

What is the anomaly called when a direct microscopic counts of natural samples reveal for more organisms than those recoverable on plates?

Answer 6

The great plate anomaly

Question 7

What are the two reason why the Great Plate Anomaly occurs?

Answer 7

1. ) Microscopic methods count dead cells, whereas viable methods do not
2. ) Different organisms may have vastly different requirements for growth