Microbiology: Chapter 6 True / False Flashcards

1) An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell.

2) Bacterial growth refers to an increase in the numbers of cells in a bacterial culture.

3) Pure cultures can easily be obtained on streak plates, even if the desired bacteria are present in very low concentrations in the initial culture broth.

4) Agar is used as a solidifying agent in microbiological media since few bacteria can degrade it.

5) Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases.

6) Most pathogenic bacteria are thermophiles.

7) In performing a ten-fold dilutions series from a sample containing 10,000 bacteria per milliliter, the fourth tube in the dilution series will have 10 cells per milliliter.

10) Nitrogen-fixing bacteria, such as cyanobacteria, can use atmospheric nitrogen (N2) for their nitrogen source.

8) Turbidity is an indirect measurement of bacterial growth that can be measured using a spectrophotometer.

9) Filtration methods, followed by growth of the bacteria trapped on the filters in growth media, are used to count bacteria present in very low concentrations, such as in lakes and streams.