energy and ecosystems Flashcards
explain eutrophication
growth of algae blocks light so plants cant photosynthesise at low levels of water and die. saprobiont populations rise and use oxygen when respiring, so fish cant respire and die
what is biomass
total mass of living material in a specific area at a given time
fresh mass advantage and disadvantage
easy to get, unreliable due to water
dry mass disadvantages
animals must be dead so only obtain a small sample size so not representative
what is bomb calorimetry
sample is weighed, burnt in oxygen, heat gained from water from combustion rises the water temp. this finds chemical energy store in DRY MASS
nitrogen cycle order
nitrogen fixation ammonification, nitrification, denitrification
nitrogen fixation
nitrogen fixing bacteria convert n2, using nitrogenase enzyme, from atmosphere into nh4+ so they can make amino acids. when they die released into soil.other sources include lightning
ammonification
saprobionts secrete enzymes and release ammonia into soil
nitrification
nitrosomonas convert nh4+ to nitrite no2- oxidise
nitrobacter convert no2- to nitrate no3- oxidise
important to have ploughed oxygenated soil so this can happen
denitrication
under anaerobic conditions, denitrifying bacteria convert no3- to n2. therefore need good soil
name some po43- compounds
dna, rna, phospholipid
what is the mutualistic relationship between nitrogen fixing bacteria and legumes
nfb give plant amino acids, plant gives nfb carbohydrates
what does mycorrhizae do
increase sa for plant roots to uptake minerals and water(by active trans)
enables plant to resist drought
improves uptake of scarce ions
what do saprobionts do
add ammonium ions to soil by breaking down nitrogen containing compounds like amino acids into nh4+
how does crop rotation increase yields
each type of crop needs diff minerals
crops are susceptible to diff diseases
why d plants need nitrogen
use it for growth. when available, plants likely to have greater leaf area, greater rate of photosynthesis, greater productivity
why does more nitrogen in water mean more fish
more nitrogen so more plants as they need nitrogen for growth. so more producers so populations of fish will rise as less competition for food and more consumers
effects of fertiliser
leaching
eutrophication
reduced species diversity
why is sun a bad source of energy
not all wavelengths can be absorbed
light may not hit chlorophyll
why is there a low npp transfer
bones not eaten
some not digested
some lost in faeces
some lost as heat from respiration esp in mammals due to high body temp
NPP=GPP-R
npp- after resp
gpp- total
r-resp
N=I-(F+R)
n- net production
i-food
f-lost in faceces
r-lost in resp
