53 Ecology & Global Ecology Flashcards
Primary producer
i.e. autotroph; any organism that creates its own food by photosynthesis or from reduced inorganic compounds and that is a food source for other species in its ecosystem; only transfers energy
Primary consumer
a herbivore; an organism that eats plants, algae, or other primary producers
Secondary consumer
a carnivore; an organism that eats herbivores
Tertiary consumer
a carnivore; in a food chain or web, organisms that feed on secondary consumers
Decomposers or detritivores
an organism whose diet consists mainly of dead organic matter (detritus) e.g. various bacteria, fungi, protists, and animals
Detritus
a layer of dead organic matter that accumulates at ground level or on seafloors and lake bottoms
Trophic (“feeding”) level
a feeding level in an ecosystem occupied by organisms that obtain energy from the same type of source
Food chain
simple pathway of energy flow through a few species, each at a different trophic level, in an ecosystem
Grazing food chain
ecological network of primary producers, herbivores, and the predators and parasites that consume them
Decomposer food chain
ecological network of detritus, decomposers that eat detritus, and predators and parasites of the decomposers
Primary decomposer
a decomposer that consumes detritus from plants; at the second trophic level of the decomposer food chain
Food web
complex network of interactions among species in an ecosystem formed by the transfer of energy and nutrients among trophic levels; consists of many food chains
Biomagnification
in animal tissues, an increase in the concentration of particular molecules that may occur as those molecules are passed up a food chain
Biogeochemical (“life Earth chemical”) cycle
the pattern of circulation of an element or molecule among living organisms and the environment
Soil organic matter
organic (carbon-containing) compounds of food in soil; a mixture of partially and completely decomposed detritus
Humus
decayed organic matter or detritus in soils
What are the 3 factors that affect the decomposition rate of detritus?
(1) abiotic conditions like oxygen availability, temp, and precipitation (2) quality of the detritus as a nutrient source for fungi, bacteria, and archaea that accomplish decomposition (3) abundance and diversity of detritivores
Global nitrogen cycle
the movement of nitrogen among terrestrial ecosystems, the oceans, and the atmosphere
Atmospheric nitrogen (N2)
biologically inert molecule that comprises ~78% of the air we breathe; usable by organisms only when it is reduced or fixed
How does nitrogen fixation naturally occur?
through lighting-driven reactions in the atmosphere and enzyme-catalyzed reactions in bacteria that live in the soil and oceans
What human activities alter the nitrogen cycle?
(1) cultivation of crops that harbor nitrogen-fixing bacteria (2) industrially produced fertilizers (3) burning of fossil fuels, which releases nitric oxide
Global carbon cycle
the movement of carbon among terrestrial ecosystems, aquatic ecosystems, and the atmosphere
Gross primary productivity (GPP)
total amount of carbon fixed by photosynthesis, including that used for cellular respiration, over a given time period
What two ways do primary producers use chemical energy?
cellular respiration and growth and reproduction
Net primary productivity (NPP)
total amount of biomass generated by the fixation of carbon through photosynthesis per year minus the amount oxidized during cellular respiration; energy used for growth and reproduction
Biomass
total mass of all organisms in a given population or geographical area; usually expressed as total dry weight
Ecosystem
a community of organisms that live in a specific area and the non-living surroundings
Omnivores
organisms that move between consumer trophic levels
Mutualists
two organisms that mutually transfer energy to each other
Dead zone
where dissolved oxygen is too low to support most life
Limiting nutrient
addition into the ecosystem enables more growth of the producers, which will allow transfer of biomass to more of the community e.g. nitrogen (cannot be assimilated by most organisms)
