The nutrient cycle Flashcards
Why is Nitrogen important?
1) Used in the production of Amino Acids and Proteins
2) Used to make bases in DNA
What are the forms of inorganic N?
N2, NO2, NH3
What are the stages of the N cycle?
1) Nitrogen fixation
2) Nitrification
3) Assimilation
4) Ammonification
5) Denitrification
What is nitrogen fixation?
N2 + 6H -> 2NH3 -> NH4+ this requires nitrogen fixing bacteria, Enzyme: nitrognase
Where do nitrogen fixing bacteria live?
Bases of the roots of leguminous plants
How else can Nitrogen be fixed?
The Haber Process (N2 + 3H2 -> 2NH3)
Spread as nitrogen fertiliser
What is nitrification?
NH4+ -> NO3- by nitrifying bacteria
Exothermic process so bacteria make ATP
What is assimilation?
The uptake of NO3- ions by plants to make amino acids and proteins
Active transport
What is ammonification?
The use of microbial saprobionts to break down dead plants, animals and waste which releases NH4+ back into the soil
What is denitrification?
The conversion of NO3- ions to N2
What should happen when solar radiation reaches the earth?
Some is reflected back into space and some is absorbed in the atmosphere and some reaches the earth
What is the greenhouse effect?
The heating affect caused by the greenhouse gases preventing radiation of heat from the earth to space
What are the greenhouse gases?
Carbon dioxide, sulphur dioxide and methane
What are the arguments against global warming?
The earth has always shown periodic fluctuation in temperature therefore we cannot say that humanity is to blame.
What are the arguments for global warming?
Atmospheric levels have increased since the start of the industrial revolution which seem to be linked to the increasing temperature.
What are the consequences of global warming?
1) Alteration in the distribution of species
2) Melting of polar ice caps thus increasing sea levels
3) Increase temp means a decrease in crop yield
What are the benefits of global warming?
Increased temperature thus increased rain fall thus increase in possible harvest (3rd world countries)
Where is phosphorous found?
In soil and rocks as phosphates (PO43-)
What is eutrophication?
The build up of excess nutrients such as nitrogen a phosphate which negatively effects an ecosystem
What are the steps in eutrophication?
1) Excess fertiliser to be added to soil
2) Excess fertiliser transported to other parts of the community
3) Algae and bacteria experience exponential growth
4) All available O2 is used by algae and bacteria
5) Other species in the eco system die as a result
What are the uses of phosphorous?
1) DNA
2) ATP
