P2 4c cycles within the ecosystem Flashcards
how does water enter the atmosphere?
as water vapour by
- energy from the sun heating and evaporating water from oceans, rivers and lakes
- or transpiration from plants releases water
how does air rise?
warmer air from the lower atmosphere rises, taking the water with it
what happens as air rises?
- moist air cools down as it rises
what happens to water as the air rises?
water vapour condense back into liquid water, forming clouds
how does water return to earth?
by precipitation
- as water droplets in the cloud get bigger and heavier they begin to fall as rain, snow or sleet
why is there a carbon and nitrogen cycle?
there is a finite amount of carbon and nitrogen on the planet so it needs to be recycled to allow new organisms to be made and grow
how is carbon taken out of the atmosphere?
in the form of carbon dioxide, by plants used for photosynthesis
how is carbon passed on to animals and microorganisms?
by feeding
how is carbon returned to the atmosphere?
in the form of carbon dioxide as a result of respiration (from plants and animals)
and in increasing amounts by the combustion of fossil fuels
what happens if animals die in conditions where decomposing microorganisms are not present?
the carbon in their bodies can be converted over millions of years and with pressure into fossil fuels
where is carbon stored?
in fossil fuels
what are the effects of mass deforestation on the carbon cycle?
its reducing the amount of producers
what is nitrogen required for?
to make proteins
can animals and plants absorb nitrogen from the air?
no because the the gas is very stable, so big amounts of energy would be needed to break them.
how is nitrogen taken out of the air?
- nitrogen fixing bacteria
- lightning can ‘fix’ N2 gas
they both convert it to be easier to absorb
how does nitrogen fixing bacteria convert N2 into something easier to absorb
- found in free living soil and also root nodules of peas beans and clover
- they take the gas and change it into nitrates in the soil
how does lightning convert N2 into something easier to absorb
- splitting the bond between the two atoms and turning them into nitrous oxide
- like N2O and NO2
- they dissolve in rainwater and leach into the soil
what do plants do with nitrates?
absorb the nitrates they find in the soil and use the nitrogen to make proteins
how do animals get nitrates?
animals eat plants or other animals and get the nitrogen they need from the proteins
how does nitrogen end up back in the soil?
by waste (urine and faeces) - send back to the soil as ammonium compounds (urea contains nitrogen)
what is another way nitrogen can end up back in the soil?
animals and plants die, they then decay and all the proteins inside them are broken down into ammonium compounds and put back into the soil be decomposers
how do plants absorb the ammonium compounds?
they can’t so a second type of soil bacteria, nitrifying bacteria convert the ammonium compounds to nitrites then to nitrates
what bacteria is found in poorly aerated soil?
denitrifying bacteria
what does denitrifying bacteria do?
the anaerobic bacteria take the nitrates out of the soil and convert them back into gas
how can denitrifying bacteria be stopped?
ploughing and turning over the soil
