Ecosystems Flashcards
biosphere
only part of earth where living things inhabit a restricted zone
ecosystem
a stable settled unit consisting of a community of organisms interrelated with the physical and chemical environment
components of an ecosystem
habitat, population, community
niche
role of each species in an ecosystem including: how/what feeds on, what it excretes, how it reproduces
why are ecosystems dynamic
living elements grow/die, non-living elements change, populations fall/rise, interact with each other and environment
types of dynamic changes affecting population size
cyclic, directional, unpredictable/erratic changes
cyclic changes
changes repeat themselves in a rhythm e.g. tides
directional changes
go in one direction and tend to last longer than lifetime of organisms, variables increase/decrease e.g. erosion
unpredictable/erratic changes
no rhythm/constant direction e.g. lightning
autotrophs
organisms that make their own food from the substances available in their surroundings using light/chemical energy e.g. producers
heterotrophs
cannot synthesise their own food so rely on other organisms e.g. consumers
trophic level
level a particular organism holds/feeds in, in a food chain
pyramid of numbers
the width of each block is proportional to the number of organisms present at each trophic level
pyramid of biomass
the mass of material for each trophic level
how biomass is lost at each trophic level
life processes within living organisms, dead organisms/waste material only available to decomposers
pyramid of energy
measured in productivity, rate at which energy passes through each trophic level
how to get dry mass
ecologist collects organisms, puts in oven at 80’C until all water evaporated by checking periodically the mass until it stops reducing
why is dry mass more difficult
the method is destructive so mostly just calculated from wet mass using previously published data
gross primary productivity (GPP)
the rate at which plants convert light energy into chemical energy
net primary productivity (NPP)
difference between GPP and plant respiration (R)
concept of increasing primary productivity
manipulating environmental factors to make energy conversion more efficient
concept of increasing secondary productivity
humans manipulating the energy transfer
endotherms
organisms with a constant body temperature (birds/mammals)
ectotherms
varying body temperature (worms, fish, reptiles)
would endo/ectotherms be more efficient to farm
ectotherms because they have a varying body temperature so are able to change to keep it stable and not waste energy
climax community
the final stable community that exists after the process of succession has occurred
succession
progressive change in a community of organisms over time
pioneer species
the species that begin the process of succession, often colonising an area as the first living things there
deflected succession
when succession is stopped/interfered with e.g. golf course, garden, garden pond
primary succession
the change in a species composition over time in a habitat that hasn’t been previously inhabited
as the distance from the shore increases, the sand…
becomes more stable and succession towards a climax community begins
secondary succession
changes in original community/habitat changing species composition over time in a habitat that has been previously inhabited
a plagioclimax
sub-climax community that develops resulting from deflected succession
sere
each stage of succession
biotic potential
maximum rate at which a population could increase under ideal conditions, different species have different biotic potentials
abiotic factors
non-living components of an ecosystem that affect other living organisms
biotic factors
environmental factors associated with living organisms in an ecosystem that affect each other
quadrant
an instrument used to measure angles
saprotrophs
bacteria/fungi that feed on dead and decaying matter
saprotrophic decomposition
saprotrophs secrete enzymes onto dead, waste material
digest material by extracellular digestion into small molecules which absorb into body
molecules are stored/respired to release energy
when does saprotrophic decomposition most occur
warm, moist conditions and more active when plenty of oxygen
most plants take up nitrogen in which 2 forms
ammonium and nitrate
processes of bacteria in the nitrogen cycle
ammonification, nitrogen fixation, nitrification, denitrification
deamination
saprophytic fungi/bacteria decompose proteins via amino acids to ammonia when organisms die
