Nutrient Cycles Flashcards
What is problem with combustion in carbon cycle
Combustion fossil fuels unbalances cycle
How is deforestation problem in carbon cycle
It stops plants from dealing with extra co2 from combustion of fossil fuels
Less plants = less photosynthesis to remove co2 from atmosphere
Describe role of saprobiotic organisms in the carbon cycle
They secrete enzymes onto dead organisms to break molecules into smaller ones
Molecules then absorbed by diffusion
This carbon released as co2 when decomposer respires
What are the 2 important greenhouse gases
Co2 and methane
How do greenhouse gases lead to global warming
Make atmosphere thicker so heat can’t escape
Heat close to earth’s surface so earth gets hotter
When is methane produced
When micro organisms break down organic molecules
How does climate change lead to loss of species
Affects the niches available in a community
Explain why co2 concentration of the atmosphere is less on a summer’s day than on a winter’s day
Summer = more light + temperature = more photosynthesis
How does nitrogen in atmosphere become ammonium-containing molecules
Only plants called legumes
They have mutualistic bacteria which can fix nitrogen
How do nirate ions become ammonium-containing molecules
Absorbed by active transport
How does nitrogen in the air become ammonium ions?
Nitrogen is fixated by free living bacteria
How does ammonification occur
Saprobiotic feeders release ammonia which then forms ammonium ions in the soil
How does denitrification occur
Only occurs in water logged soil where there’s lack of oxygen
As there’s more anerobic bacteria which converts soil nitrates into gaseous nitrogen
How does nitrite (no-2) become nitrate (no-3)
Nitrification:
Oxidation occurs from O2 in air
Allowed to happen by free living aerobic bacteria in soil that is nitrifying bacteria
How does ammonium ions become nitrite (no-2)
Nitrification:
Oxidation occurs from O2 in air
Allowed to happen by free living aerobic bacteria in soil that is nitrifying bacteria
What is the first 2 stages in eutrophication
NO-3 is limiting factor
NO-3 is leached into water so no longer limiting factor so plants grow exponentially
What are the eutrophication stages after NO-3 is leached into water
Algal bloom
Algae absorb all light so lower plants have none
Light becomes limiting factor for lower plants
So lower plants die
What are the eutrophication stages after the lower plants die
Dead plants are no longer limiting factor for saprobiotic organisms which grow exponentially
Saprobiotic organismsuse O2 for respiration so less O2
O2 becomes limiting factor for aerobic organisms
What are the eutrophication stages after O2 becomes the limiting factor for aerobic organisms
Lake life die so more NO-3
Less aerobic organisms so less competition for Anerobic organisms which grow exponentially
What are the eutrophication stages after anaerobic organisms grow exponentially
Anaerobic organisms decompose their material so more NO-3 and toxic waste
Substance released at same time
Hydrogen sulphide produced
Water known as putrid
Describe the carbon cycle
Co2 in air Photosynthesis by plants Plants consumed by animals Plants + animals respire Plants + animals die Micro organisms respire
Extra = combustion fossil fuels
What is organic/natural fertiliser
Dead and decaying remains of plants and animals and animal waste
What is inorganic/artificial fertiliser
Mined rocks and deposits then converted into different forms and blends
What does research show about fertilisers
A combination or organic and inorganic fertilisers leads to the greatest long-term increase in productivity
Why are fertilisers needed in agricultural ecosystems
Crops are repeatedly grown on same area of land
Minerals taken up by crops aren’t returned as crop consumed away from land
Mineral ion levels in soil reduced
This limits rate of photosynthesis
Fertilisers used to replace mineral ions
What are the effects of nitrogen fertilisers
Reduces species diversity
Leeching
Eutrophication
How does nitrogen fertiliser reduce species diversity
Nitrogen rich soils favour the growth of rapid growing species (eg grass) which out-compete many other species
What is leeching
Pollution of watercourses
What causes eutrophication
Leeching of fertiliser into watercourses
