PLS 366 EXAM 3 QUESTIONS & ANSWERS
Macro - Answers ->2 mm. Earthworms. Mosses.
Meso - Answers -00.1-0.2mm. Mites.
Micro - Answers -<0.1-0.2mm. Bacteria. Nematodes.
Chemoheterotrophs - Answers -Energy from reduced organic C. Source of carbon is
organic C.
Chemoautotrophs - Answers -Energy from Oxidation of inorganics. Sources of C is
CO2.
Photoautotrophs - Answers -Energy from light. Sources of C is CO2.
Photoheterotrophs - Answers -Energy from light. Source of carbon is organic C.
Crustose Lichen - Answers -Weathering of Rock Symbiotic relationship between fungi
and cyanobacteria
Aflatoxicosis - Answers -disease caused by consumption aflatoxin
Importance of Fungi - Answers -Breakdown of organic residues and formation of
humus
Mycorrhizal fungi - Answers -Symbiosis between certain fungi
and roots of plants
Fungi obtain C from plant root cells
Fungal hyphae explore large volumes of soil for nutrients, improving nutrient
availability(P) and water uptake
Actinomycetes - Answers -Resemble mini fungi but are bacteria. Aromatic compounds -
geosmin
("earth smell")
Cyanobacteria - Answers -Photosynthetic
bacteria
• Numerous in wetland
soils and aquatic
environments
Obligate Aerobes. Obligate Anaerobes - Answers -Required to exist for soil aeration
Facultative anaerobes - Answers -Not required soil aeration
, Temperature OM - Answers -Warm to cold, OM increases
Precip OM - Answers -Dry to Wet, OM increases
Building soil OM - Answers -Reduce tillage and other disturbance
Increase intensity of cropping
Increase yields
Re-vegetation
Enhanced pasture/range management
Compost - Answers -End product of aerobic decomposition of organic materials outside
of soil.
Materials to Use: tree leaves, grass clippings, weeds, kitchen scraps etc. Avoid meat
scraps, plastics, glass
Denitrification - Answers -Bacterial reduction of NO3
- to N2(g) and N2O (g)
Conditions for Denitrification - Answers -•Lack of free O2
•Available organic C
•Warm soils best
•Available NO3
Haber-Bosch process (1914) - Answers -Human made energy
Biological Nitrogen Fixation - Answers -Catalyzed by an enzyme: nitrogenase
Symbiotic N-Fixation - Answers -Rhizobia-legume symbiosis
-Host plant supplies bacteria with carbs
-Bacteria supplies the plant with N -Rhizobiumforms nodules on roots
Inorganic N - Answers -Plant available N.
NH4+ and NO3-
Organic N - Answers -•Proteins, DNA, Nucleotides, Amino-sugars, Amino-acids, etc...
•Living Biomass
N oversupply results in... - Answers --Excessive vegetative
growth
-Lodging
-Delayed plant maturity
-Increased diseases
susceptibility
-Degraded fruit/grain quality and taste
Macro - Answers ->2 mm. Earthworms. Mosses.
Meso - Answers -00.1-0.2mm. Mites.
Micro - Answers -<0.1-0.2mm. Bacteria. Nematodes.
Chemoheterotrophs - Answers -Energy from reduced organic C. Source of carbon is
organic C.
Chemoautotrophs - Answers -Energy from Oxidation of inorganics. Sources of C is
CO2.
Photoautotrophs - Answers -Energy from light. Sources of C is CO2.
Photoheterotrophs - Answers -Energy from light. Source of carbon is organic C.
Crustose Lichen - Answers -Weathering of Rock Symbiotic relationship between fungi
and cyanobacteria
Aflatoxicosis - Answers -disease caused by consumption aflatoxin
Importance of Fungi - Answers -Breakdown of organic residues and formation of
humus
Mycorrhizal fungi - Answers -Symbiosis between certain fungi
and roots of plants
Fungi obtain C from plant root cells
Fungal hyphae explore large volumes of soil for nutrients, improving nutrient
availability(P) and water uptake
Actinomycetes - Answers -Resemble mini fungi but are bacteria. Aromatic compounds -
geosmin
("earth smell")
Cyanobacteria - Answers -Photosynthetic
bacteria
• Numerous in wetland
soils and aquatic
environments
Obligate Aerobes. Obligate Anaerobes - Answers -Required to exist for soil aeration
Facultative anaerobes - Answers -Not required soil aeration
, Temperature OM - Answers -Warm to cold, OM increases
Precip OM - Answers -Dry to Wet, OM increases
Building soil OM - Answers -Reduce tillage and other disturbance
Increase intensity of cropping
Increase yields
Re-vegetation
Enhanced pasture/range management
Compost - Answers -End product of aerobic decomposition of organic materials outside
of soil.
Materials to Use: tree leaves, grass clippings, weeds, kitchen scraps etc. Avoid meat
scraps, plastics, glass
Denitrification - Answers -Bacterial reduction of NO3
- to N2(g) and N2O (g)
Conditions for Denitrification - Answers -•Lack of free O2
•Available organic C
•Warm soils best
•Available NO3
Haber-Bosch process (1914) - Answers -Human made energy
Biological Nitrogen Fixation - Answers -Catalyzed by an enzyme: nitrogenase
Symbiotic N-Fixation - Answers -Rhizobia-legume symbiosis
-Host plant supplies bacteria with carbs
-Bacteria supplies the plant with N -Rhizobiumforms nodules on roots
Inorganic N - Answers -Plant available N.
NH4+ and NO3-
Organic N - Answers -•Proteins, DNA, Nucleotides, Amino-sugars, Amino-acids, etc...
•Living Biomass
N oversupply results in... - Answers --Excessive vegetative
growth
-Lodging
-Delayed plant maturity
-Increased diseases
susceptibility
-Degraded fruit/grain quality and taste
