lecture 2 walker

Question 1

what is an ecosystem

Answer 1

species and their habitats

–> this is more of a community actually

Question 2

population

Answer 2

single species in a location

Question 3

niche

Answer 3

area within a habitat that supplies a particular species / community with factors for their survival. Niches Often define organism relationships within an ecosystem.

Question 4

what is the microbial loop?

Answer 4

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.

Question 5

t or f, Organic matter is lost in the microbial loop.

Answer 5

false!! organic matter (OM) is recycled not lost

Question 6

how does the land trophic levels differ from the ocean trophic levels?

Answer 6

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

Question 7

what is the ocean food web?

Answer 7

• considered a biological pump
• microbes capture and energy and consume energy
• yields dissolved organic matter, CO2 and energy

Question 8

explain organic matter turn over time, land vs sea

Answer 8

land - 10 years or so

sea - much faster (week)

Question 9

What is an Aerobic environment ?

Answer 9

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)

Question 10

what is an anaerobic environment?

Answer 10

microbes use minerals (Fe+3 and NO-) to oxidize compounds. Often CO2

Question 11

lichens are a symbiotic relationship between cyanobacteria or algae with fungi –> what is their relationship?

Answer 11

mutualism

Question 12

explain the relationship of algae and fungi (lichen)

Answer 12

they are so intimate they collectively produce a molecule called soredia. This is a cyanobacteria wrapped in the hyphae of the fungi

Question 13

explain cooperation symbiosis

Answer 13

less intimate relationship then lichens. In these situations the organisms do fine on their own butu they benefit from living in the same community

Question 14

what is an example of a cooperative relationship

Answer 14

many bacteria recycle chemicals between themselves.

Question 15

explain the rhizoplane/rhizosphere relationship.

Answer 15

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

Question 16

what is mycorrhizae

Answer 16

the fungi under the ground which grow near trees. they produce fruiting bodies called truffles. This is what we eat.

Question 17

why cant you grow truffle in a garden?

Answer 17

the fungi need the cooperative relationship with the tree. The fungi protect the tree, in turn the tree provides essential nutrients.

Question 18

what are rhizobia?

Answer 18

the microbes the infect plants. once the plant is completely infected nitrogen fixation can occur

Question 19

briefly explain the mutualistic relationship of legumes and rhizobia

Answer 19

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

Question 20

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

Answer 20

fuck

Question 21

N2 + 8e +2H –> 2NH4 +H2

what rxn is this

Answer 21

nitrogen fixation. this is very expensive!! takes 8 electrons! these 8 electrons are coming from the plant. plant utilizes ammonia ions

Question 22

t or f, rhizobium is one of the only things able to break nN2 bonds

Answer 22

true

Question 23

50% of ammonium production is done by legume rhizobia interactions

Answer 23

true

Question 24

vampircoccus bacteria is an example of ?

Answer 24

predation

Question 25

P. syringae bacteria is an example of what?

Answer 25

parasitism

Question 26

epiphytes are?

Answer 26

organisms that live on plants

Question 27

some plants inhibit quorem sensing within bacteria! t or f

Answer 27

true

Question 28

what is the biogeochemical cycle?

Answer 28

the metabolic interactions between microbial communities and ecosystems.

Question 29

carbon > oxygen > nitrogen > hydrogen

Answer 29

dry weight % of elements in microbes

Question 30

explain the carbon dioxide cycle

Answer 30

carbon cycles between CO2 and reduced forms of carbon found in biomass. carbon cycling is dependent on O2 presence

Question 31

what is occurring in the arctic and the carbon cycle

Answer 31

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

Question 32

what are gas hydrates?

Answer 32

ancient microbes produce and release methane surrounded in a cage of water in permafrost. The water cage stabilizes the methane.

Question 33

lightning is the only other contribution of nitrogen fixation other then microbes, t or f?

Answer 33

true

Question 34

what are the 5 steps of the nitrogen cycle?

Answer 34

1. N fixation = production of organic N from N2/NH3 2. mineralization = organic N turned into NH4 3. nitrification = NO3 produced 4. denitrification = NO3 makes N2 5. anammox rxn = NH4 and NO2 make N2. this rxn is enabled by microbes

Question 35

what performs mineralization of organic nitrogen?

Answer 35

fungi and bacteria (decomposers) which make ammonia

Question 36

t or f, not a single microbe can do nitrification

Answer 36

true, it must be a cohort. the product if nitrification is nitrate

Question 37

what is the anammox step?

Answer 37

mostly done by archaea. Anammox stands for anaerobic ammonium oxidation. Nitrification and denitrification can be skipped straight to the anammox rxn.