Energy and ecosystems A2 Flashcards
what happens to the majority of the sun’s energy when not used in making organic matter
it is reflected, the wrong wavelength, light misses the chlorophyll molecule used in respiration of producer
equation of net productivity
net productivity = gross productivity - respiratory losses
how is energy lost between trophic levels
in respiration
as heat
in excretory products
movement
what’s the maximum number of trophic levels most food chains have
5
units for energy flow
kJm^-2 year
what is the unit for biomass
gm^-3
define biomass
the total mass of living material in a specific area at a given time
pros and cons of dry biomass
overcomes the problem of varying volumes of water in an organism but you must kill organism to find this
how do you remove water from a sample of biomass
recording mass and heating until a constant mass is recorded
what shape are pyramids of numbers and why
any shape because it doesn’t account for size of organism
cons of pyramids of numbers
there’s often so many individuals it’s hard to show on a scale
doesn’t show seasonal differences
why is conversion of food to biomass lower in colder temperatures
lose more heat
more respiration
more energy used in respiration
equation for energy transfer (% efficiency)
energy available after transfer/energy available before transfer
what is the purpose of an agricultural ecosystem
to improve productivity
how is an ecosystem prevented form reaching natural climax community
decrease species diversity
methods to improve productivity
adding fertilisers using pesticides using greenhouses/irrigation systems ploughing covering crops with nets intensive farming selective breeding
why use greenhouses/irrigation system
to remove limiting factors of photosynthesis
why use nets to cover crops
to protect from birds
why plough
improve drainage and increase O2 for saprobionts in nitrogen cycle
how do factory farms intensively farm animals
restrict movement
keep warm
no predators
feeding controlled
why do factory farms restrict movement of their animals
less energy being used for muscle contraction and more on growth
why do factory farms keep warm
less energy spent keeping warm and more for growing
how to estimate energy store in biomass
calorimetry
define biomass
formed from the biological molecules of plants
can be measured in terms of carbon or dry mass of tissue, per given area, per time
