lecture 2 walker Flashcards
what is an ecosystem
species and their habitats
–> this is more of a community actually
population
single species in a location
niche
area within a habitat that supplies a particular species / community with factors for their survival. Niches Often define organism relationships within an ecosystem.
what is the microbial loop?
microbes are a crucial part of an ecosystem at all consumer levels. As we go up trophic levels the biomass decreases and therefore the carbon flux decreases too. microbes are very important to be primary consumers and producers.
t or f, Organic matter is lost in the microbial loop.
false!! organic matter (OM) is recycled not lost
how does the land trophic levels differ from the ocean trophic levels?
on land aside from microbs,
primary consumers are cattle and primary producers are plants. In the ocean both primary producers and consumers are microbes. No metazoa in the ocean food web
what is the ocean food web?
- considered a biological pump
- microbes capture and energy and consume energy
- yields dissolved organic matter, CO2 and energy
explain organic matter turn over time, land vs sea
land - 10 years or so
sea - much faster (week)
What is an Aerobic environment ?
microbes use oxygen as an electron acceptor to make organic compounds such as CO2. Others use oxygen to respire (often involves oxygen combining with NH3)
what is an anaerobic environment?
microbes use minerals (Fe+3 and NO-) to oxidize compounds. Often CO2
lichens are a symbiotic relationship between cyanobacteria or algae with fungi –> what is their relationship?
mutualism
explain the relationship of algae and fungi (lichen)
they are so intimate they collectively produce a molecule called soredia. This is a cyanobacteria wrapped in the hyphae of the fungi
explain cooperation symbiosis
less intimate relationship then lichens. In these situations the organisms do fine on their own butu they benefit from living in the same community
what is an example of a cooperative relationship
many bacteria recycle chemicals between themselves.
explain the rhizoplane/rhizosphere relationship.
microbes on the roots (rhizoplane) or in surrounding soil (hizosphere). Plant supply microbes with nutrients. Bacteria release antibiotics which kills pathogenic bacteria. This is called plant pro-biotics. This is still cooperation
what is mycorrhizae
the fungi under the ground which grow near trees. they produce fruiting bodies called truffles. This is what we eat.
why cant you grow truffle in a garden?
the fungi need the cooperative relationship with the tree. The fungi protect the tree, in turn the tree provides essential nutrients.
what are rhizobia?
the microbes the infect plants. once the plant is completely infected nitrogen fixation can occur
briefly explain the mutualistic relationship of legumes and rhizobia
endophytes (bacteria infecting plant e.g. rhizobia) colonize internal plant tissue and promote plant growth with hormones. the rhizobia uses plant resources to perform nitrogen fixation
upon initial infection of rhizobium, the legume produces nitrogen peroxide to kill them. Rhizobium has powerful antioxidants allowing it to survive. Plant also produces flavonoids. Rhizobium detect these and start swimming towards the plant and they bind plant root hairs. After this, genes in rhizobium called nod factors were turned on by flavonoid binding. These nod factors then help indicate to the plant to curl around the bacteria. Calcium helps membrane fusion. Then an infection thread develops to allow bacteria to enter down into the plant for nitrogen fixation
fuck
N2 + 8e +2H –> 2NH4 +H2
what rxn is this
nitrogen fixation. this is very expensive!! takes 8 electrons! these 8 electrons are coming from the plant. plant utilizes ammonia ions
t or f, rhizobium is one of the only things able to break nN2 bonds
true
50% of ammonium production is done by legume rhizobia interactions
true
vampircoccus bacteria is an example of ?
predation
P. syringae bacteria is an example of what?
parasitism
epiphytes are?
organisms that live on plants
some plants inhibit quorem sensing within bacteria! t or f
true
what is the biogeochemical cycle?
the metabolic interactions between microbial communities and ecosystems.
carbon > oxygen > nitrogen > hydrogen
dry weight % of elements in microbes
explain the carbon dioxide cycle
carbon cycles between CO2 and reduced forms of carbon found in biomass. carbon cycling is dependent on O2 presence
what is occurring in the arctic and the carbon cycle
shit tonne of carbon is chilling in the arctic permafrost. As the climate is warming, this permafrost is melting which allows carbon to be released to the atmosphere. decomposers use the released carbon. This further increases temperature which allows more vegetation to grow in the tundra. The vegetation utilizes CO2 to make O2. This is going to become dried out which will cause fire which causes more CO2. It is a positive feedback cycle
what are gas hydrates?
ancient microbes produce and release methane surrounded in a cage of water in permafrost. The water cage stabilizes the methane.
lightning is the only other contribution of nitrogen fixation other then microbes, t or f?
true
what are the 5 steps of the nitrogen cycle?
- N fixation = production of organic N from N2/NH3
- mineralization = organic N turned into NH4
- nitrification = NO3 produced
- denitrification = NO3 makes N2
- anammox rxn = NH4 and NO2 make N2. this rxn is enabled by microbes
what performs mineralization of organic nitrogen?
fungi and bacteria (decomposers) which make ammonia
t or f, not a single microbe can do nitrification
true, it must be a cohort. the product if nitrification is nitrate
what is the anammox step?
mostly done by archaea. Anammox stands for anaerobic ammonium oxidation. Nitrification and denitrification can be skipped straight to the anammox rxn.
