Energy Transfer - Energy and Ecosystems Flashcards
what is a producer?
a photosynthetic organism that manufactures organic substances using the sun’s energy
what is a consumer?
An organism that feeds on another organism
what is a trophic level?
a stage in a food chain
what are saprobionts?
organisms that break down the complex material in dead organisms into simple ones
what is biomass?
the total mass of living material in a specific area at a given time
what is a food web?
a series of linked food chains
what is a food chain?
a linear representation of the feeding relationship in an ecosystem
what is the ultimate source of energy in all ecosystems?
sunlight
how is sunlight conserved in plants?
as chemical energy
what do most plants use sunlight for?
making organic substances, usually sugars
what are the two forms of biomass?
fresh mass
dry mass
what is fresh mass?
all of the biomass of an organism
what is dry mass?
the biomass of an organism when all the water has been removed
what is an advantage of using fresh mass?
it is easy to access
what is a disadvantage of using fresh mass?
different organisms have varying amounts of water so not representative of the amount of other biological molecules present
what is an advantage of using dry mass?
it is more reliable
what are the disadvantages of using dry mass?
time consuming
organisms have to be killed
what are the units for biomass?
dry mass per given area
eg kg m-2
how can the energy at each trophic level be calculated?
collect a sample of the organism
weigh sample
burn in pure oxygen in a sealed chamber called a bomb
measure temp increase in a fixed volume of water
calculate energy released
why is energy lost between the sun and a producer?
over 90% of sun’s energy reflected into space
not all wavelengths can be absorbed
light may not hit the chlorophyll
why is energy lost between the producer and primary consumer?
some plant material cannot be accessed (eg roots)
some cannot be digested
excretory losses
respiratory losses
death and decay
why is energy lost between consumers?
excretory and respiratory losses
indigestible material
movement
death + decay
what is gross primary production?
the total amount of chemical energy converted from light energy in plants, in a given area
what is the equation for net primary production in plants?
NPP = GPP - respiration losses
what is the equation for npp in animals?
NPP = I - (F + R)
or
net primary production = food ingested - (faeces + respiration losses)
what is the equation for energy efficiency?
energy available after transfer divided by energy available before transfer
then x100
what is ammonification?
the production of ammonium ions from ammonium containing compounds
what carries out ammonification?
saprobionts
what is nitrification?
the production of nitrate ions from ammonium ions
what carries out nitrification?
nitrifying bacteria
what are the stages of nitrification?
ammonium ions
nitrite ions
nitrate ions
what is nitrogen fixation?
converting nitrogen gas into ammonium ions
what causes nitrogen fixation?
lightning
mutualistic bacteria living in plant root nodules
free living bacteria
what is denitrification?
converting nitrates into nitrogen gas
what causes denitrifiction?
anaerobic conditions
denitrifying bacteria
what is assimilation?
when plants take up nitrate ions from the soil
draw a diagram of the phosphorus cycle
what is guano?
accumulation of seabird faeces
what assists plants in the absorption of phosphate ions?
mycorrhizae
what is mycorrhizae?
the mutualistic relationship between fungi and the roots of plants where the fungi help absorb minerals for the plant and the plant provides organic compounds for the fungi
how do the fungi help increase the uptake of minerals in mycorrhizae?
they increase the surface area of the roots of the plant
what is eutrophicaton?
the prescence of excessive nutrients in a waterway, causing the death of fish and plants
why are fertilisers used?
in natural ecosystems the minerals removed are returned by dead plants/animals
in farming they are not returned as crops are harvested so need fertilisers to replace lost minerals
what is leaching?
the washing away of water soluble compounds in the soil
what are the types of fertilisers?
natural/organic
artificial
what do natural/organic fertilisers contain?
dead + decaying remains of plants+animals as well as waste such as slurry and manure
what do artificial fertilisers contain?
pure chemicals as powders or pellets
