soil and water

Question 1

soil

Answer 1

organic (rare) or inorganic

complex, heterogenous environment and immense microbial diversity

Question 2

soil formation

Answer 2

complex, takes 1000s of years, affected by microbial (metabolic products = organic acids, co2), plant and animal activities, and physical and chemical processes (freeze-thaw, wind/water erosion, dissolution)

Question 3

primary producers in aquatic env

Answer 3

microbes (eg phytoplankton)

Question 4

organic soil

Answer 4

created by decomposition of organic matter in bogs and marshes, much higher level of organic matter than inorganic matter, fairly rare but v productive

Question 5

inorganic soil

Answer 5

most common

Question 6

microbial activites in soil

Answer 6

metabolic products, organic acids, CO2

Question 7

animal contribution to soil

Answer 7

mixing and aerating upper layers

Question 8

plant contribution to soil

Answer 8

taking up water, releasing organics into soil (as they die)

Question 9

soil profile layers

Answer 9

O: exposed organic matter on surface
A: topsoil, lots of minerals, root zone, lots of microbes, active
B: subsoil, less available minerals, some microbes (spare populations), somewhat active
C: mostly inorganic matter, resembled bedrock (crumbled), sometimes have microbes (spare and metabolically inactive mostly)
Bedrock

Question 10

microenvironments in soil aggregates

Answer 10

clay, mineral, organic matter sufaces

water, air-filled pores

Question 11

determinants of microbial activity in soil

Answer 11

water –> affects o2 (which will affect aerobes!)

nutrient status –> microbial activity limited by C, N, or P availability

Question 12

how the soil aggregate microenvironments can change

Answer 12

introduction of organic matter (eg fungi)

Question 13

is the oxygen [] of a microenvironment constant

Answer 13

no; the aerobic microbes will quickly use up the O content, and then O-dependent microbes will die, or have to switch to a different form of metabolism

Question 14

do all soil have the same microbial communities?

Answer 14

v few microbes are common to all soil samples, immense diversity

Question 15

rhizosphere

Answer 15

soil that surrounds plant roots, significantly different than bulk soil environment –> known as rhizosphere effect
large amounts of organic carbon due to plant excretion, therefore a higher number of microbes can grow here

Question 16

rhizosphere effect

Answer 16

the difference in bulk soil env. vs plant soil env. bc plants greatly influence soil habitat + serve as potential habitat

Question 17

rhizoplane

Answer 17

actual root surface

source of root exudates –> sugar, AAs, hormones, vitamins

Question 18

phyllosphere

Answer 18

surface of plant leaf

Question 19

subsurface inhabitants of terrestrial env; describe them

Answer 19

prokaryotes and microeukaryotes; low metabolic activity (bc low nutrient habitat)

Question 20

most important parts of aquatic environment composition

Answer 20

O2 and sunlight

Question 21

freshwater environment O2 levels

Answer 21

O2 produced near surface, lower O2 at greater depths bc of low solubility and consumption (aka anerobic inhabitants in deeper regions)

Question 22

photic zone

Answer 22

areas of aquatic environment that are reached by sunlight; microbes in that environment are able to photozynthesize

Question 23

startified lake

Answer 23

at certain times of years, it forms layers and those layers don’t mix - wind and waves would mix it but this doesn’t happen

Question 24

thermocline

Answer 24

temperature changing v quickly over a short area (bc of the sunlight not reaching the bottom anymore)
anoxygenic photosynthesis by H2S-oxidizing organisms

Question 25

environment types arranged by relative # of prokaryotes (most to least)

Answer 25

ocean subsurface (below 200m), terrestrial subsurface, soil, ocean surface, domestic animals, atmosphere

Question 26

structure of stratified lake

Answer 26

areobic, thermocline, anaerobic

Question 27

deepest region of a lake

Answer 27

anaerobic, support anaerobic heterotrophic activity and NO3- reduction
anerobic decomposition in sediment

Question 28

rivers as an aquatic environment features

Answer 28

flow and turbulence affect degree of re-oxygenation

organic matter and nutrient input may affect productivity and lead to o2 depletion

Question 29

BOD

Answer 29

biochemical oxygen demand = change in dissolved oxygen after 5 days
a measure of amount of organic matter in water that can be oxidized by microorganisms

Question 30

types of marine environemtns

Answer 30

open ocean

fre

Question 31

types of marine environemtns

Answer 31

open ocean

inshore areas

Question 32

open ocean as a microbial environment

Answer 32

low 1o productivity, often limiting N, P, Fe resulting in low heterotrophic activity

Question 33

inshore ocean as a microbial env

Answer 33

nutrient rich, greater productivity

Question 34

deep sea habitats as a microbial environment

Answer 34

75% of ocean water is at depths greater than 1000m

dark, cold, under high hydrostatic pressure, low nutrient input therefore low microbial activity

Question 35

types of microbes in deep sea

Answer 35

psychrotolerant or pshcryophillic, piezotolerant (barotolerant), or piezophilic (piezotolerant)

Question 36

relativity abundance of archaea and bacteria in deep sea

Answer 36

archaea more abundant than bacteria, bacteria are at a relatively constant low level in the deep sea

Question 37

how do hydrothermal vent communities survive?

Answer 37

geothermal energy
H2S is used most of the time by bacteria as the form of primary energy (since there are no photons available)
CO2 and CH4 also present and can be used

Question 38

what are the types of hydrothermal vent communities?

Answer 38

free-living microorganisms

microbe-animal symbiosis

Question 39

what are the types of hydrothermal vent communities?

Answer 39

free-living microorganisms

microbe-animal symbiosis

Question 40

types of free-living microorganisms in hydrothermal vents

Answer 40

S-oxidizing chemolithotrophs (Thiothrix, Beggiato, Thiobacillus) - both auto (as 1o producers) and hetero (as 2o)
may also be H2-, Fe+, Mn+ oxidizers, methanotrpohs, nitrifiers
may also be methanogens, S0-reducers, sulfate-reducers,Fe(III) reducers

Question 41

types of microbe-animal symbiotes in hydrothermal vents

Answer 41

S-oxidizers and tube worms, clams, mussels

animals that graze directly on microbiota

Question 42

tube worm features

Answer 42

2m long
no mouth, anus, gut
possess trophosome (spongy tissue w S granules) and S-oxidizing bacteria
will trap O2, H2S and deliver it to the S-oxidizing bacteria
byproducts of S-oxidizing bacteria supports tube worm growth

Question 43

how is the hydrothermal vent habitat different from the one we’re used to thinking about?

Answer 43

we’re used to light + CO2 being consumed by phototrophs and autotrophs –> driven by light
hydrothermal vent communities consume H2S and CO2 by chemolithoautotrophs and autotrophs –> driven by geothermal energy
both end up being consumed by organotrophic and heterotrophic organisms