Question

1. Relationship between microbial growth and absorbance?

2. Relationship between microbial growth and percent trnsmittance?

3. Why is it that the density of a cell suspension is expressed as absorbance rather than percent transmission?

4. Why is it that one needs to use a blank (medium only) when measuring bacterial growth using a spectrophotometer?

5. What are the functions of the following?

A. Selective media

B. Differential/ selective media

C. Enriched media

6. Why is blood agar enriched media?

7. Explain the following

A. Crystal violet in th MacConkey agar medium?

B. Blood in the blood agar medium?

C. High salt concentration in the mannitol salt agar?

D. Lactose in the MacConkey agar medium?

8. Describe th following groups of organisms according the the oxygen needs?

A. Aerobes

B. Microphilies

C.Obligate anaerobes

D. Aerotolerant

E. Facitilative anaerobea

9.Describe the shake tube inoculation technique. What growth characteristic of microorganisms is this technique used to determine?

10. Why is it that aerobic organisms will not grow in fluid thiogycollate medium but anaerobic organisms will?

11. What dose a pink coloration in fluid thigycollate medium indicate? Presence or absence of oxygen?

12. How is oxygen removed from the jar in ththe gaspak system?

13. How would you know if you have established and anaerobic environment in the gaspak? What indicate is used to determine this? What color will the indicator be in an anaerobic environment? What color will the indicato be in and aerobic environment?

14. Describe how the pour plate technique can be us d to count bacterial colonies. What is it important to perform s rial dilutions in your bacterial culture and plate cells of various dilutions in the serial dilutions agar plate technique?

15. What plates are suitable for containing the serial dilution agar plate techniques?

16. How would you report th results of a plate that contains 400 colony forming units? 25 colony forming units?