6.3 Ecosystems Flashcards
habitat definition
where an organism lives
biotic factors examples
interspecific and intraspecific competion for food/nutrient
predation
disease
abiotic factors examples
wind speed temperature light intensity CO2 conc. soil/water pH humidity weather
biotic factors definition
how living organisms affect the distribution of other organisms
abiotic factors definition
non-living factors in an ecosystem that can affect the distribution of organisms
niche definition
the role of an organism in an ecosystem
community definition
all of the populations of different species who live in the same place at the same time and can interact with each other
population definition
all of the organisms of one species who live in the same place at the same time and breed together
ecosystem definition
any group of living organisms and non-living things occuring together and the interrelationships between them
producer definition
organism that produces organic molecules using sunlight energy
consumer definition
organism that eats other organisms
decomposer definition
organism that breaks down dead or undigested organic material
trophic level definition
stage in food chain occupied by a particular group of organisms
e.g. producers are first trophic level
energy transfer through ecosystems
photosynthesis is the main route energy takes to enter an ecosystem
sunlight energy converted to chemical potential energy and stored as biomass
biomass/energy is transferred when organisms eat other organisms e.g. producer -> primary consumer -> secondary consumer etc.
energy locked up in things that cant be eaten e.g. bones, faeces broken down and recycled back into ecosystem by decomposers
biomass definition
dry mass of organic material on an organism
function of food chains and food webs
food chains show simple lines of energy transfer
food webs show lots of food chains in an ecosystem and how they overlap (shows interdependence between organisms)
why biomass is lost from food chains at each trophic levels
some food cant be eaten (e.g. bones)
energy released from organic molecules e.g. CO2 and heat from respiration lost
waste products and dead organisms contains biomass only available to decomposers
least efficient transfer and why
producers and primary consumers as they lack cellulase to digest cellulose cell walls
some parts of producers may not be eaten e.g. roots
pyramid of numbers
shows numbers of species in a food chain
area of bar proportional to numbers of individual
why its rare for chains to go past 4/5 trophic levels
energy is lost from food chain at each trophic level
limited energy transferred from one level to next
limits length of food chains
top consumers unable to eat enough animals at level below to provide sufficient energy to live
pyramids of biomass
shows biomass at each trophic level
takes into account size of organisms and mass of material at each level
problems of constructing pyramids of biomass
organisms heated in oven to evaporate all water
weighed periodically until all water evaporated and mass doesn’t reduce more
destructive as organism dies
instead wet mass measured and dry mass is estimated using old published data
productivity definition
rate of production of new biomass
rate of energy flow through each trophic level
productivity units
kg/MJ m^-2 yr^-1
net primary productivity formula
gross primary productivity - respiration
