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. symbiosum
AAGTGGTCAGG
2.
P. occultum
GAGCGGTCGGG
3.
E. coli
AAGCGTTAATC
4. clone p7l2-3 GAGTGGTAGCC
Based on these data alone:
Which two organisms are most closely related?
Which are the most distantly related?
EXPLAIN
how 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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