5.4 Nutrient Cycles Flashcards
What do saprobionts (decomposers) do?
Break down dead animals and plants allowing elements to be recycled
They digest their food externally and absorb the nutrients they need - called extra cellular digestion
What is the role of mycorrhizae?
A fungi that forms a symbiotic relationship with the root of plants
The plant has the ability to gather nutrients and water through the fungus
In exchange the fungus gets sugars from the plant from photosynthesis
Where is nitrogen found in the body?
DNA RNA Amino acids Nucleic acids ATP
What are the four main processes in the nitrogen cycle?
Nitrogen Fixation
Ammonification
Nitrification
Dentrification
What is nitrogen fixation?
The conversion of gaseous nitrogen into nitrogen compounds
It can occur naturally with lightening
Or using nitrogen fixing bacteria
What is ammonification?
Saprobiotic bacteria decompose proteins and urea into ammonium compounds
What is nitrification?
Ammonium is oxidised into Nitrite and Nitrate
Carried out by nitrifying bacteria in the soil
What is dentrification?
Nitrates are broken down by organisms and the nitrogen is released into the atmosphere from aerobic respiration
Uses de-nitrifying bacteria
What contains phosphorus?
ATP/ADP Phospholipids TP and GP RuBP NADP
Where is phosphorus found?
Contained in sedimentary rocks
What is the phosphorus cycle?
Animals eat phosphates in plants
Plants and animals die
Phosphates in detritus are either decomposed into soil/water
Or turned into sediments and fossils (which the phosphates in soil or water also turn into)
The sediments and fossils as well as phosphates in soil and water will assimilate into organic phosphates in plants
What are some advantages and disadvantages of natural fertilisers?
Can be recycled from elsewhere
Improves microbial biodiversity of the soil
Require the break down from microorganisms so takes longer
The mineral quantities aren’t specifically known
What are some advantages and disadvantages of artifical fertilisers?
They immediately release their ions into the soil
Known mineral quantities
Doesn’t promote microbial growth as no decay required
Can lead to over fertilisation/ toxic build up
What is eutrophication?
An excessive increase in nitrogen or phosphorus that can lead to algal blooms and lake death
What are the stages of eutrophication?
Leaching of artificial fertilisers leads to increased nitrate in water
Plants now grow exponentially leading to algal bloom on surface which decreases light intensity lower down
Plants lower down die and saprobiots feed on the dead using aerobic respiration, using O2
O2 decreases so organisms die and anaerobic organisms increase - which further decomposes dead material releasing more nitrates
Low O2 and high nitrates = putrid water
