2952131774-quiz_2a_key

2952131774-quiz_2a_key - Mic102/Win08/Appleman Quiz 2, 13...

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Mic102/Win08/Appleman Quiz 2, 13 February 2008 This quiz is to represent only your own work . As a UC Davis student, you are bound by an honor code; if you can’t be trusted with that, can you be trusted in a career in, say, the health professions? This quiz is closed book, closed note. Please hand in a blue scantron with the answers to the multiple choice section of the quiz. Make sure that it has your name, student I.D.#, and “ Test form A ” filled in. You will also need to hand in the last two pages of this quiz, with your name on each. Deep sea hydrothermal vents are amazing places. Discovered in the 1970’s, these are areas where the plates that make up the earth’s crust are moving apart, and ocean water percolating through the sea floor can be exposed to the hot rocks of the earth’s interior. The water comes back, rushing out of these vents at very high temperatures and saturated with reduced minerals. These vents support ecosystems that have some fascinating inhabitants; the ecosystems are remarkable in that they are completely independent of the sun. Nonetheless, they are some of the most productive ecosystems in the world, converting matter and energy into living material at a faster rate than a well-tended corn farm!
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We’ve already met one of the organisms that lives in these geothermal vents—the hyperthermophilic Archaean “strain 121”. It was grown in the laboratory in minimal medium under anaerobic conditions. The medium contained formate (HCOO-) as the only source of carbon, Fe +3 oxide, and ammonia. As the organism grew, it produced magnetite (Fe +2 oxide; in the figure, tube A1 contains the organism, while tube A2 does not). 1. Which of these happens when strain 121 generates energy? a) electrons go from formate to ammonia b) electrons go from ammonia to formate c) electrons go from formate to Fe +3 --Iron is getting reduced, and something else must be getting oxidized—formate. d) formate is fermented anaerobically 2. Strain 121 is an autotroph. How could the researchers determine this? a) it has the gene for Rubisco— not likely, given that it’s Archaea b) it grows in the absence of fixed carbon—this is by definition. c) it has genes for the oxidative Krebs cycle— there are other options d) it has nitrogenase 3. Autotrophy requires high energy electrons. How does strain 121 get high energy e-? a) energizing e- from formate by reversing the flow of e- through an electron transport chain b) photosystem I c) electrons from formate are at very high energy already, and can reduce ferredoxin—see table of reduction potentials. d) electrons are moved through ATPase 4. Strain 121 has an unusual membrane structure—a monolayer of phytanyl diethers. What characteristic(s) of this membrane is/are important for strain 121’s energy
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2952131774-quiz_2a_key - Mic102/Win08/Appleman Quiz 2, 13...

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