Exercise 9

Exercise 9
Questions
1. When an agar plate is inoculated, why is the loop sterilized after the initial
inoculum is put on?
2. Distinguish between a pure culture and a mixed culture.
3. Define a bacterial colony. List four characteristics by which bacterial
colonies may be distinguished.
4. Why should a Petri dish not be left open for any extended period?
5. Why does the streaking method you used to inoculate your plates result in
isolated colonies?
6. Why is it necessary to isolate individual colonies from a mixed growth?
7. Why was a blood agar, rather than a nutrient agar, plate used for the
culture from your mouth?
8. Are the large numbers of microorganisms found in the mouth cause for
concern? Explain.
9. How do microorganisms find their way into the mouth?