Nitrogen And Symbioses Flashcards
What is the haber Bosch process ?
This process is used to make artificial ammonia, nitrogen fertilisers.
How many tonnes of nitrogen fertiliser are used in farming per year ?
100 million tonnes
What is the enzyme that is used in diazotrophs to fix nitrogen and what is its structure ?
Nitrogenase complex. Consists of two proteins; Fe protein and MoFe protein.
How does the nitrogenase complex work ?
Fe protein takes electrons by oxidising ferredoxin. MoFe uses electrons (x8) from ferredoxin and energy from ATP (x16) to reduce N2 to NH3.
What and where do cycads form a nitrogen symbiosis ?
Form symbiosis with Cyanobacteria which are diazotrophic. These are found in the corraloid roots.
What and where do water ferns form a nitrogen fixing symbiosis?
Form symbiosis with diazotrophic Cyanobacteria in leaves.
Where does big myrtle form a symbiosis with Frankia ?
In root nodules.
What is the role of laghaemaglobin in root nodules ?
Nitrogen fixation In rhizobia needs to occur in anaerobic conditions. Laghaemaglobin lines the inside of nodules mopping up oxygen to create this environment.
Explain the process that initiates nodulation.
When a plant is lacking nitrogen and has excess carbon fixed, they release flavonoids. These in turn activate nod genes in rhizobia to sunsequently release nod factors. Nod factors dive roots injections of hormones which cause nodule formation.
What genes fix nitrogen ?
Nif/ fix genes.
What do rhizobium gain from their relationship with legumes ?
Fed with COH, fe, mo and s. These in turn optimise fixation.
What do legumes gain from their relationship with rhizobia ?
Ammonia with which they can further assimilate.
