MB 495 C/D - Microbial Diversity - Spring 1995

Midterm Exam #2

1. Given the following tree, which organism is most primtative with respect to rRNA sequence ______, and which is most advanced______. (5 points)

2. After obtaining an interesting rRNA sequence from a survey of an environmental sample, how could you identify the morphology of the organism represented by that sequence? (5 points)

3. Why is a thermostable DNA polymerase, e.g. that of Thermus aquaticus, useful for polymerase chain reaction (PCR) amplification? (5 points)

4. Why are the purple Bacteria & relatives sometimes refered to as the "proteobacteria"? (5 points)

5. Why is Pseudomonas not a coherent phylogenetic group? (5 points)

6. Name a terminal electron acceptor other than molecular oxygen than can be used for autotrophic growth. (5 points)

7. What is the fundamental unusual feature of the Gram-positive cell envelop? (5 points)

8. Describe one way in which oxygenic photosynthesizers can fix nitrogen despite the strong inhibition of nitrogenase by oxygen. (5 points)

9. How do the stalks of Planctomycetes differ from those of the prosthecate a-purple Bacteria? (10 points)

10. Describe briefly how molecular phylogenetic analysis can be used to survey organisms in an environment without the use of cultivation. (10 points)

11. How is taxis (e.g. chemotaxis) different in spirocheates relative to most other Bacteria? (10 points)

12. Describe (diagrammatically if you wish) the life cycle of the bacterial parasite/predator of other Bacteria, Bdellovibrio. (10 points)

13. Describe how the bacterial electron transport chain can be the foundation of bacterial phenotypes as diverse as photosynthesis, sulfur oxidation, sulfur reduction, iron oxidation, and heterotrophy, to name a few. (10 points)

14. Name That Organism! (2 points each)