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  1. Define metabolic diversity and explain the benefits of having this ability.
    • Metabolic diversity: to be able to use a variety of carbon and energy sources, and to grow under different physical conditions
    • The benefits of metabolic diversity are that microbes can inhabit almost any area on the planet, and be diverse amongst eachother so that they cannot be wiped out simultaneously from removing or changing a single condition.
  2. List the 4 biogeochemical cycles
    • Carbon cycle
    • Nitrogen cycle
    • Sulfur cycle
    • Phosphorous cycle
  3. Describe/diagram the nitrogen cycle
    • Decomposition: proteins/waste products -> A.A. [microbes]
    • Ammonification: A.A. -> ammonia (NH3) [microbes]
    • NOTE - In dry soil NH3 is released into the atomoshpere but it wet soil NH3 is converted to NH4+ ions in the water.
    • Nitrification: NH4+ --(Nitrosomonas)-> NO2- --(Nitrobacter)-> NO3- [performed by soil bacteria]
    • Denitrification: NO3- --(Pseudomonas)-> N2 [as alternate e- acceptor]
    • Nitrogen Fixation: N2 -> NH3 [very few microbes, Rhizobium is example]
  4. Describe/Diagram the Carbon cycle
    • Photosynthesis: CO2 -> organic material by photoautotrophs
    • Heterotrophy: Chemoheterotrophs eat photoautotrophs
    • (Some CO2 released during respiration by heterotrophs, most C retained until excreted as waste or organism dies)
    • Decomposition: Bacteria or fungi, CO2 released.  Some released when fossil fuels are combusted.
  5. Describe/Diagram the Sulfur cycle
    • Decomposition: proteins/waste products -> A.A. [microbes]
    • Dissimilation: A.A. (-SH) -> H2S
    • H2S --(Thiobacillus)-> SO42- (for energy) -> A.A.
    • Anaerobic respiration: SO42- (for energy) -> H2S
  6. Describe/Diagram the Phosphorous Cycle
    • Exhibits very little change to oxidation state, instead rotates between soluble/insolube
    • Insoluble PO43- --(acid)-> Soluble PO43-
    • Solube PO43- --(bird guano)-> Insoluble PO43-
  7. List/describe associations of bacteria with some different organisms and list/describe some specific examples of each
    • Animals: Normal bacterial flora
    • Cows carry ruminants in the rumen which digest cellulose
    • Bioluminescent bacteria in flashlight fish
    • Insects:
    • ants live in association with fungi,
    • aphids live in associations with bacteria
    • Plants:
    • Agrobacterium (parasitic association, forms crown galls)
    • Rhizobium (mutualistic association, form nodules)
    • Mycorrhizae (extend surface area of roots, mulutualistic)
  8. List/Describe various zones of a pond in terms of oxygen availability and light penetration and the organisms that live in each zone
    • Littoral zone: along shore (producers, plants)
    • Limnetic zone: surface of open water (algae, cyanobacteria)
    • Profundal zone: deeper water, under limnetic zone (anaerobic purple and green photosynthetic bacteria)
    • Benthic zone: bottom sediment, often no light, little O2 (Desulfovibrio, Methanogens, Clostridium - obligate anaerobes)
    • Seawater light depths: Surface (unicellular green algae, diatoms, dinoflagellates, plants) Red (multicellular green algae) -> orange (brown algae) -> yellow -> violet (red algae) -> blue (red algae)
  9. Define coliform bacteria and explain their importance in water quality testing
    • Aerobic or facultatively anareobic, gram-negative, non-endospore forming rods that ferment lactose to acid + gas within 48 hours at 35C
    • They are indicator organisms used to detect fecal contamination in water.

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2012-11-27 13:32:57

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