Biology 260 Quiz #3 – take home/open book Due 8/6/12 25 points 1. Discuss and explain the difference between facultative anaerobes and obligate anaerobes. In your discussion, name and briefly explain the function of enzymes produced by organisms able to tolerate an oxygen environment. 2. How is the anaerobic environment created in an anaerobe jar used to culture obligate anaerobes? 3. What are the two mechanisms bacteria use for the repair of thymine dimers? 4. How do thymine dimers result in mutations? 5. What are two ways bacteria can protect themselves against UV damage? 6a What is the clear zone around the discs called? 6b. What does the zone mean how do we interpret the result? How does this interpretation differ for detergents or other chemicals versus antimicrobial drugs? 7. Why do we standardize the media, innoculum age/size and incubation period for clinical susceptibility testing? 8. What type of medium is Mannitol salt agar? 9. What type of organisms does MSA select for? How? 10. What type of organisms does it differentiate? How? 11. What is the purpose of controls used in scientific experiments? What is a positive control? A negative control?