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Sample test 2A key

Sample test 2A key - Mic102/Fa09/Appleman Quiz 2 18...

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Mic102/Fa09/Appleman Quiz 2, 18 November 2009 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? Not only does this honor code demand personal integrity, but it also requires you to demand integrity from your peers. 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. There are many deep-sea environments that are rich in methane and sulfate but are anaerobic. Methane plus sulfate represents energy, and where there is water and energy, there is life. This energy is exploited by a syntrophic consortium of an Archaean called “ANME” that consumes methane and a Bacterium called “DSS” that consumes sulfate. Neither grows or consumes its substrate without the other. Syntrophy itself is not unusual. What makes this association stand out is its energetic poverty: processing a mole of substrates generates barely enough energy to make a mole of ATP, and that must be divided between two organisms! The ANME-DSS syntrophy is a strong contender for the world’s most energetically wretched lifestyle. A month ago, a report by Anne Dekas from Caltech found that the ANME archaean was capable of fixing nitrogen—a remarkable finding, given the energy demands of azotrophy and the energy scarcity of ANME’s environment. Two weeks ago, a group from the Max Planck Institute in Germany published the genome sequence of an ANME archaean, answering some questions but raising others. Hopefully, somebody will sequence the DSS bacterium soon!
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1. The ANME-DSS syntrophy grows in an environment with just CH 4 , CO 2 , SO 4 - and N 2 . Using the redox table, how are the ANME-DSS organisms generating energy? a) respiration, with methane serving as e- donor and sulfate serving as e- acceptor. If you use the redox table, you will observe that methane can donate electrons to sulfate exergonically. b) respiration, with sulfate serving as e- donor and methane serving as e- acceptor —this is ENDERGONIC c) fermentation, with methane serving as e- donor and e- acceptor— this is biologically impossible d) respiration, with methane serving as e- donor and N2 serving as an e- acceptor— you should know that reducing N2 takes lots of energy. Plus, I left it off the table! 2. The ANME-DSS consortium is autotrophic: it can be grown in an environment with just CH 4 , CO 2 , SO 4 - and N 2 —no fixed carbon or nitrogen. This is a) suprising, because autotrophy requires chlorophyll— NO NO NO NO NO NO!!!!
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