Pack 15 - Nutrient Cycles Flashcards
What is nitrogen fixation?
process by which nitrogen gas is converted into nitrogen-containing compound that is useful to organisms
converts nitrogen into ammonia via reduction
How is nitrogen fixation carried out?
Nitrogen fixing bacteria
What is nitrification?
changing ammonium ions into nitrates
How is nitrification carried out?
nitrifying bacteria
What are the two stages of nitrification and what carries them out?
1) oxidation of ammonium to nitrite by nitrifying bacteria
2)oxidation of nitrites to nitrates by nitrifying bacteria
ammonium -> nitrites -> nitrates
What is denitrification?
loss of nitrates from the soil under anaerobic conditions
nitrates are converted to nitrogen gas by reduction reactions
How is denitrification carried out?
By denitrifying bacteria
What is the flow of nitrogen through the food web?
inorganic nitrogen is taken up by plants in the soil in the form of nitrates
used for the synthesis of nitrogen contating compounds such as DNA
This then moves onto other organisms when the plant is eaten, digested and the organic compound is absorbed
What is decomposition and ammonification?
When an organism containing organic nitrogen dies saprobionts convert the organic nitrogen locked up inside the compounds into ammonia
the ammonia is then converted to ammonium compounds in the soil
What is the phosphate cycle?
Movement of phosphate through the different trophic levels
no atmospheric gas involved
What is Mycorrizae?
a mutualistic relationship between a fungus and the root of a plant in which they both benefit nutritionally
What are fertilizers?
they add important ions required for the plant to grow i.e proteins - nitrates nucleic acids - nitrates and phosphates phospholipids - phosphate ATP - nitrates and phosphates
Why do fertilizers reduce species diversity?
increase growth of species means that they outcompete other growing species which then die as a result
What is Eutrophication?
an algal bloom occurs due to a large amount of fertilizer in a body of water which causes them to grow exponentially
dense layer of algae forms on the surface of the water absorbing light and preventing it from reaching lower depths
plants below surface die
increased competition between algae means algae dies too
when the algae and plants die, there is more decomposition that takes place by bacteria and saprobionts (whos population will have increased)
increase in aerobic respiration as bacteria uses up oxygen
dissolved oxygen in the water becomes depleted so many species of invertebrates and fish will die
