recycling within ecosystems Flashcards
what is the term given to how bacteria and fungi feed
saprotrophically
explain how sapotrophic decomposition occurs
1- bacteria and fungi secrete enzymes on dead material
2- enzyme digest material and saprotrophs absorb
3- molecules absorbed are stored and respired
why is it not possible for nitrogen to be used by organisms directly
because nitrogen is unreactive
what are the two forms of fixed nitrogen
nitrates
ammonium (NH4+)
what is an azotobacter-
bacteria which live in soil and fix nitrogen to ammonium
what is rhizobium
bacteria in root nodules of legumes, provide plant with fixed nitrogen, recieve glucose in return
what does it mean if bacteria is mutualistic
it means it is in a relationship where organisms benefit eachother
what enzyme does azotobacter and rhizobium both contain in order to convert nitrogen and hydrogen to ammonia
nitrogenase enzyme- convert nitrogen and hydrogen to ammonia
what does it mean by the term nitrogen fixation
nitrogen gas into compounds such as ammonia
what organism produce ammonification
decomposers
what is ammonification
keeps nitrogen fixed as ammonia in the soil. does this by taking urea, nucleic acids from soil and fixing it into ammonia
what is nitrification
when nitrogen is taken by roots
what type of plant does rhizobium live in the root nodules of
legumes- plants such as peas, beans and clovers.
what is leghaemoglobin and what does it do
protein in the root nodules which absorbs oxygen and keeps environment anaerobic for bacteria to use enzymes effectively
nitrogen is fixed naturally from the atmosohere through what occurence
lightning strikes and fixed nitrogen
what is the difference between nitrification and nitrogen fixation
nitrification is process of coverting ammonium- nitrite- nitrate by bacteria nitrosomonas and nitrobacter
nitrogen fixation is fixing nitrogen gas to ammonium by bacteria rhizobium and azotobacter
what process are rhizobium and azotobacter involved in
nitrogen fixation
what process are nitrosomonas and nitrobacter involved in
nitrification
what does nitrosomonas do
oxidise ammonium to nitrite
what does nitrobacter do
oxidise nitrite to nitrate
after rhizobium and azotobacter have made ammonium what happens next
nitrosomonas and nitrobacter nitrify it into nitrites then nitrates which is soluble by roots
what is denitrification
when bacteria convert nitrates back to nitrogen gas
what location and conditions does denitrification occur
anaerobic condition in water logged soil
why does nitrification occur in well aerated soil
nitrosomonas oxidises ammonium to nitrites
nitrobacter oxidise nitrite to nitrate
oxidation can only occur with oxygen therefore soil needs to be well aerated
