Midterm I, 1998 Questions from Dr. Fuhrman:1. (7 points) Draw a phylogenetic tree, based upon 16S rRNA sequences (and scaled to indicate approximate evolutionary distances based upon those sequences), including the following. Just put the letters on the tree, to make it easier A. Human B. Gram Positive Bacteria C. Chloroplasts D. Mitochondria E. Thermoacidophilic archaea F. Slime molds G. Cyanobacteria H. E. coli(in the Purple bacteria) I. Wheat J. Methanogenic archaea K. Giardia (a protist lacking mitochondria) 2. (5 points) The following partial aligned sequences were determined for the 16S rRNA genes of four real organisms: I. C. symbiosumAAGTGGTCAGG 2. P. occultumGAGCGGTCGGG 3. E. coliAAGCGTTAATC 4. clone p7l2-3 GAGTGGTAGCC Based on these data alone: Which two organisms are most closely related? Which are the most distantly related? EXPLAINhow you came up with your answers, showing all the comparisons you made. 3. (6 points) A. How did the evolution of cyanobacteria change the Earth's atmosphere (in two sentences or less)? B. Briefly (2 sentences or less each) describe two consequences of this atmospheric change that had dramatic effects on the evolution of orgarnisms other than cyanobacteria. One should involve UV light and the other should involve energy metabolism. 4. (9 points) Matching. Put the one letter corresponding to the closest match by each number on the left. Some letters may not match anything, and letters can be used more than once. One point for each correct answer: _____1. Bacteria A. Can cause toxic "red tides"_____2. Archaea B. Have shells made of calcium carbonate_____ 3. Ciliates C. Fossil microbial mats_____4. Diatoms D. Use formylmethionine intitiator tRNA
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