The Nutrient Cycle Flashcards
State the five stages of the nitrogen cycle
Nitrogen Fixation
Decomposition
Ammonifocation
Nitrification
Denitrification
Explain Nitrogen fixation in the nitrogen cycle
Nitrogen fixing bacteria (found either on legume nudules or free living) convert Nitrogen gas into ammonia and ammonium ions.
How are nitrogen fixing bacteria found on nodules beneficial for legume plants?
The bacterium recieves water and sugar from the plant and in return provodes the plant with ammonia, which is used to make proteins and nitrogen cintaining compounds
Explain the process of ammonification in the nitrogen cycle
When microorganisms die or excrete faeces, saprobiotic microorganisms convert organic nitrogen containing compoiunds into ammoinia and ammonium ions.
They do this via extracellular digestion
Products of digestion are absorbed by the saprobionts or released into the environment
Explain the process of ammonification in the nitrogen cycle
When microorganisms die or excrete faeces, saprobiotic microorganisms convert organic nitrogen containing compoiunds into ammoinia and ammonium ions.
They do this via extracellular digestion
Products of digestion are absorbed by the saprobionts or released into the environment
Explain the process of nitrification in the nitrogen cycle
Nitrifying bacteria convert ammonium ions into nitrates, via two oxidation reactions (first to NO2- then to NO3-)
The nitrates are taken up by plant roots by active transport, for the biotic phase
Explain the process of denitrification in the nitrogen cycle
Nitrates from the soil are converted back into nitrogen gas under anaerobic conditions. Done by denitrifying bacteria
Explain the process of the phosphorus cycle
Sabrobionts decompose waste materials using extracellular digestion.
They absorb the products of digestion and release phosphate ions into soils lakes amd rivers.
Some ohosphate ions are absorbed by plants and algae and used for growth
The phosphate ipns passed to animals that feed on the plants and algae. Phosphate containing compounds are digested and absorbed.
Some phosphate ions in lakes rivers and oceans can form rocks by sedimentation- then returned to the cycle if erosion occurs
Name biological molecules that phosphorus is important in
ADP, ATP, nucleic ackds, phospholipids, NADP, NADPH
What are Mycorrhizae?
Fungi that grow in association with plant roots to improve the plants uptake of water and inorganic ions
Explain how Plants and Mycorrhizae form a mutualistic relationship
The fungus colonizes the host plants roots, they grow to produce a large system of threads or hyphae
This provides the fungus with carbohydrates from the plant like glucose and sucrose
In return the plant can absorb more water and minerals from the fungus due to its karger surface area
Why are fetilisers useful?
Nitrates and ohosphates are sometimes limiting factors in plant and algal growth
Intensive food production causes them to be lost from the soil as crops are harvested
No plants are left to decompose, so minerals are not recycled so fertilisers are used to replace the lost mineral ions and maintain crop production
What are the three most important inorganic ions found in fertilisers?
Nitrates, phosphates and potassium ions
What is the difference between natural and artificial fertilisers?
Natural- consist kf organic plant or animal matter, containing complex organic compounds
Artificial- manufactured and contain concentrated mineral ions in an inorganic, soluble form
State three environmental consequenses of using articficial fertilisers
Decreased species diversity
Leaching
Eutrophication
Explain what leaching is?
Where excess ions from fertilisers can be washed out of the soil by rain
The leached ions spread to streams, rivers and lakes
This can lead to eutrophication
Explain the process of eutriphication
Leaching causes an algal bloom to form
A dense layer of algae forms on surface of water, absorbing light so it cannot penetrate the water, plants below surface cannot photosynthesis so die
Increases competition between algae also results in death of algae
Dead plants are decombosed gy asprobionts, whose population increases. Therefore more aerobic respiration decreases oxygen conc.
Many species and fish then die
How can pollution of a river with sewage also cause eutrophication?
Organic material in sewage is fed upon by saprobionts, which respire aerobically and use up pxugen
Np respiration
If detergents contain ohosphates are present, algal growth is promoted
