Unit 5: energy transfer in & between organisms Flashcards
define community
all the living organisms that live in a habitat at the same time
define population
the number of the same species that live in a habitat at the same time
define ecosystem
a community in conjunction with the non living components of the environment
define abiotic
the non-living, chemical and physical components of the ecosystem
define biomass
the total mass of living matter within an organism
how can the amount of biomass remaining in an organism be measured
in terms of:
-mass of carbon
-dry mass of tissue per given area
why is dry mass used instead of wet mass
wet mass can vary too much- unreliable results
define calorimetry
a technique used to measure the quantity of heat gained/lost by a system
what is calorimetry used for
to estimate the chemical energy store in dry biomass
process of calorimetry
carried out in a bomb calorimeter, in which a sample of known mass is burnt in pure oxygen.
the bomb calorimeter is submerged in water and therefore the change in water temperature can be used to calculate the energy in the sample
define gross primary production
the chemical energy store in plant biomass, in a given area or volume
-it is the total energy resulting from photosynthesis
define net primary production
the chemical energy store in plant biomass taking into account the energy that will be lost due to respiration (R)
formula to calculate net primary production
NPP= GPP - R
NPP is the energy left over that is available to the plant to create new biomass and therefore available to the next trophic level in a food web
formula to calculate the net production of consumers (N), such as animals
N = I - (F+R)
I= chemical energy store in ingested food
F= chemical energy lost to environment in faeces and urine
R= respiratory loses
what units are used to record rates of productivity
kJ ha-1 year-1
-kJ is unit for energy
-recorded as per unit area to standerdise the results to enable environments to be compared, takes into accounts different environments will vary ins size
-per year to take into account the impact seasons will have on rain, light and heat- provides an annual average to allow fair comparisons between environments
explain the reasons why a low % of energy is transferred between trophic levels
-some of the organism is not consumed
-some parts cannot be digested
-some energy is lost in excretory substances
-some energy lost from respiration, lost to the environment
formula to calculate efficiency of energy transfer between trophic levels
percentage efficiency= (energy available after the transfer/energy available before the transfer) X 100
example of how farmers are reducing respiratory losses within a human food chain and why this is important
importance- reduce energy loss and increase yield
e.g. keeping animals in confined spaces to reduce muscle movement and keep the, warm to reduce heat loss (ethical concerns)
how is production affected by simplifying food webs
by simplifying food webs it aims to reduce energy losses to non-human food chains
e.g. reduce/eliminate organisms being farmed (crops compete with plants for water, space, light etc.)
nitrogen cycle stages
ammonification
nitrification
denitrification
nitrogen fixation
describe ammonification
this is the production of ammonia from organic nitrogen containing compounds.
-saprobiontic microorganisms feed on faeces and dead organism materials, releasing ammonia which then forms ammonium ions in the soil
-the nitrogen returns to the non living component of the ecosystem
describe nitrification
oxidation reactions occur which release energy, and this is carried out by nitrifying bacteria:
-oxidation of ammonium ions into nitrite ions
-oxidation of nitrite ions into nitrate ions
the nitrifying bacteria needs oxygen for two reasons:
-to carry out aerobic respiration
-oxygen is used for these conversions
why is it important for farmers to keep their soil structure light and well aerated
ensures that there is enough oxygen for nitrifying bacteria to carry out its function.
-ensures the plants get the nitrate they need
describe dentrification
breakdown of nitrates into nitrogen gas, by nitrifying bacteria, which is released into the atmosphere
describe nitrogen fixation
where nitrogen gas is fixed into other compounds by bacteria with a nitrogen fixing ability.
-do so by reducing nitrogen gas to ammonia which subsequently dissolves to form ammonium ions
-the relationship between nitrogen fixing bacteria and the plant is mutualistic as it is beneficial to both organisms
where is nitrogen fixing bacteria found
root nodules of leguminous plants
outline the phosphorus cycle
phosphorus exists mostly as phosphate ions in sedimentary rocks as a result of weathering.
the ions are then absorbed by plants and are incorporated into their biomass
animals obtain the ions when they feed on these plants
excess ions are excreted and may accumulate in waste material
decomposers break down these dead plants and animals which release phosphate ions into the water and soil
some of the ions are left in remains such as bone or shell, because it takes longer to decompose
the phosphate ions are then released by decomposition or dissolve out of rocks and are transported by rivers/streams into lakes/oceans where they form sedimentary rock and complete the cycle
explain the role of mycorrhizae in nutrient cycles
fungi increase the SA for absorption of water/minerals.
it also acts as a sponge in the soil so holds water/minerals in the neighborhood of roots.
this increases drought resistance and take up inorganic ions more easily
what is the relationship like between mycorrhizae and plants
mutualistic relationship
-fungi gets sugars and amino acids from the plant
-plant benefits from increased water/ion uptake
why does agriculture cause a loss in nutrients
when crops are harvested, minerals are removed and not returned upon decomposition because the crops are taken away for consumption so minerals are not replaced by their remains/waste products
why are fertilisers used
replaces the lost minerals and increases the energy efficiency of the food chain
define natural fertilisers
organic matter such as manure, sewage sludge, seaweed etc
define artificial fertilisers
inorganic material such as pure chemicals such as pure chemicals e.g. ammonium nitrate as powder/pellets
environmental issues with fertilisers
when more fertiliser is added to soils, it can be leached into waterways by rain or irrigation. this leads to eutrophication.
when is leaching more likely to occur and with which fertiliser
if the feriliser is applied just before rainfall
-artificial fertiliser is more soluble soluble
why is natural fertiliser being less soluble a benefit
the fertiliser is released slower and with more control (tends to just replace what has been taken) so it is harder to add in excess, therefore less leaching
eutrophication
causes by excess nutrients leaching into the waterways.
-provides algae in waterways with enough nitrate ions to grow more rapidly than it otherwise would do. as a result, this can block out light from other plants, causing decay and the use of oxygen in the water way. this eventually leads to the death of the ecosystem.
