Exam #3 Flashcards
what are the three domains of life?
-eukaryota
-bacteria
-archaea
generally, what type of organisms are eukaryotes?
fungi, protists, plants, and animals (membrane bound organelles with nucleus)
what type of organisms are prokaryotes?
archaea and bacteria (don’t have membrane-bound organelles)
describe the kingdom protista
very diverse eukaryotes that are a part of an “other” category that aren’t plants, animals or fungi; some can move and photosynthesize, some form colonies such as slime molds and kelp.
describe the soil trophic levels
primary producers –> primary consumers (herbivores) –> secondary consumers –> tertiary consumers
decomposers: consume all dead organic matter and release plant nutrients (all trophic levels)
primary decomposers:
>detritivores: eat dead or digested plant debris
>saphrophytes: eat dead or digested plant and animal debris (responsible for most decomposition)
what are the different size classes of soil organisms?
- macro-organisms (>2 mm)
- meso-organisms (0.1-2mm)
- micro-organisms (<0.1mm)
what organisms are considered macro-organisms?
-plant roots
-burrowing animals
-earthworms
-ants and termites
__________ _______ are macro-organisms which are ____-____ of plant mass. they are ___-______ um in diameter
plant roots
30-50%
10-400
how do plant roots enrich SOM?
roots enrich SOM with:
exudates: dissolved organic compounds exuded by roots
ex: acids, sugars, mucigel, shedded cells, dead roots
-root respiration (1/3 to 1/2 of soil CO2)
-create biopores
what is the rhizosphere? what does the rhizosphere has more of compared to non-rhizosphere soil?
zone most affected by roots (2-3cm of roots)
the soil in the rhizosphere has
-more SOM (more sugars)
-more chelates –> increased complexation
-lower nutrients (more acids)
-lower O2, more CO2 (due to more respiration)
-lower aeration
(compared to non-rhizosphere soils)
describe burrowing animals that contribute to macro-organisms and how they impact soils
diverse species and trophic levels: mammals, reptiles, insects, and amphibians (multiple ecological roles: detritivores, predators, and herbivores)
soil impacts: translocate and mix soil, create networks of biopores, and aerate soils
ants and termites have multiple ecological roles (herbivores, predators and detritivores), how do their nests impact soils?
-improved soil aeration
-increased infiltration
-modify soil pH
-local enrichment of nutrients
(habitat for ants: temperate, for termites: hot, dry)
what habitat are earthworms (Annelida) found in? what are their functions?
cool, moist aerated soil with neutral pH; most abundant animal microorganism in moist humid regions.
functions: mix soil particles and nutrients, improve soil structure (increase aggregation)
what are different types of meso-organisms?
rotifers
springtails and mites
tardigrades (“water bears”)
nematodes (unsegmented worms found in almost all soils)
protozoa
describe protozoa and where you might find them
mobile, unicellular eukaryotes of the kingdom protista (some photosynthesize). they are predators who eat bacteria, 4-250 um in size. habitat: prefer moist, aerated surface soils
what 4 things do all organisms need to survive?
-electron acceptor (oxidizing agent)
-carbon source
-water
-mineral nutrients
where do autotrophs get their carbon/energy from?
C from inorganic compounds (CO2 or CO3 2-)
where do heterotrophs get their carbon/energy from?
C from organic compounds (with C-C and C-H bonds)
where do chemotrophs get their energy from?
energy (e-) from chemicals
where do phototrophs get their energy from?
energy (e-) from light
what are chemoheterotrophs?
energy source from biochemical oxidation and carbon source from organic materials (all fungi, all animals, most bacteria)
what are chemoautotrophs?
energy source from biochemical oxidation and carbon source from CO2 (deep ocean microbes, N + S oxidizers)
what are photoheterotrophs?
energy source from sunlight and carbon source from organic materials (some bacteria, algae and protists)
what are photoautotrophs?
energy source from sunlight and carbon source from inorganic CO2 (algae, cyanobacteria, and higher plants)