Soils

Question 1

organic soils

Answer 1

decomposition of organic matter from bogs and marshes

higher (60%) of organic matter

Question 2

soil formation

Answer 2

needs 1000s of years to reach a mature soil profile
microbial activity, and other physical processes contribute
-Acids dissolve out rock material
-Water wind etc, erode
-Biological processes
-Microbes can live, using sun, are autotrophic, use rock minerals, produce organic matter and allow for more microbial activity

Question 3

O horizon

Answer 3

in the open air

in soils, its often not there as we often change it

Question 4

A horizon

Answer 4

organic matter, some nutrients, microbes, root zone, minerals

Question 5

B horizon

Answer 5

less organic matter

Question 6

C

Answer 6

mostly bed rock
not a lot of organic matter
can have microbes / living in the bed rock

Question 7

D

Answer 7

can have microbes living in the bedrock

Question 8

rhizosphere

Answer 8

richer than normal soil, absorbs acids, etc.

-surround plant roots

Question 9

determinants of microbial activity in soil

Answer 9

• water availibility, affecting O2 availibility
• nutrient status, can limit microbes with C,N,P
• adding fungals metabolize and release material helping bacterials for food

Question 10

Cold water and microbes

Answer 10

cold water is more soluble and hence is used up by aerobes and becomes anoxic

Question 11

Congregation

Answer 11

cells congregate near edges of pores as theres more nutrients there

Question 12

rhizoplane

Answer 12

root surface, source of root exudates (sugar, aa, hormones, vitamins)

Question 13

phyllosphere

Answer 13

surface of plant leaf

Question 14

Deep terrestrial surface is a microbial habitat

Answer 14

• primarily prokaryotes
• low nutrient habitat, v.low metabolic activity
• 10km below ground surface

Question 15

Aquatic environments: Freshwater - lakes

Answer 15

O2 produced near surface, depleted further down due to low solubility and consumption
anaerobic inhabitants are in deeper regions

Question 16

Epilimnion

Answer 16

oxygenic area of lake

Question 17

hypolomnion

Answer 17

anoxic region of lake

Question 18

Aquatic environments: Freshwater - Rivers

Answer 18

re-oxygenation is affected, organic matter, nutrient inputs affect productivity, leading to O2 depletion
-Biochemical Oxygen Demand (BOD) is the change in dissolved oxygen after 5 days at 20deg C (the measure of organic matter that can be oxidized by microorganisms)

Question 19

Aquatic environments: Marine - Open ocean

Answer 19

low primaryproductivity, often limiting N, P, Fe resulting in low heterotrophic activity

Question 20

Aquatic environments: Marine - Inshore area

Answer 20

nutrient rich, resulting in greater productivity

Question 21

Aquatic environments: Deep Sea

Answer 21

• cold, high hydrostatic pressure, low nutrient input
• low microbial activity; inhabitants are psychrotolerant or psychrophilic, piezotolerant (barotolerant) or piezophilic (barophilic)

Question 22

Hydrothermal vent communities

Answer 22

driven by geothermal energies

• free living organisms
• include S-oxidizing chemolithotrophs (Thiothrix, Beggiatoa, Thiobacillus)
• may also be H2-, Fe2+-, Mn2+-oxidizers, methanotrophs, nitrifiers
• may also be methanogens, S0-reducers, sulfate-reducers, Fe(III)-reducers
• microbe-animal symbioses
• S-oxidizers & tube worms, clams, mussels

-animals that graze directly on the microbiota

Question 23

tube worms

Answer 23

• possess a trophosome - spongy tissue packed with S granules and S-oxidizing bacteria
• tube worm traps O2, H2S in blood and delivers to bacteria
• bacteria grow on H2S, thiosulfate and CO2
• products of bacterial metabolism support tube worm growth