energy transfers Flashcards
energy lost between trophic levels
-some parts aren’t eaten (e.g. bones and roots)
-some parts are eaten but not absorbed (lost in faeces)
-some of the biomass is eaten and absorbed (lost in urine)
-some of the biomass is broken down is respiration (temperature regulation and movement)
reasons why energy may not be converted into biomass
-some energy is reflected back into space by the atmosphere
-not all wave lengths can be absorbed
-some light doesn’t hit the chlorophyll molecule
-other limiting factors may be involved
biomass
-the dry mass of carbon in an organism in a particular area
GPP
-the rate at which plants convert light energy into biomass during photosynthesis
NPP
-the energy stored in biomass
-it takes into account the loss in respiration
calculating NPP
N = I - ( F + R )
N= NPP
I= chemical energy store in ingested food
F= chemical energy lost in faeces and urine
R= respiratory loss
calculating energy loss
energy available after transfer / energy available before transfer x100
nitrification
NH4+ to NO3-
-nitrifying bacteria is involved
-its aerobic
-it occurs in the air spaces in the soil
denitrification
NO3- to N2
-denitrifying bacteria is used
-its anaerobic
-it occurs when the soil gets filled with water
ammonifcation
N2 to NH4+ (organic nitrogen to ammonia)
-it takes place in saprobionts (specifically in the root nodules)
-it occurs in faeces and decaying matter
nitrogen fixing
N2 to NH4+ (nitrogen gas to nitrogen containing compounds)
-it occurs in root nodules of plants (leguminous plants)
-nitrogen fixing bacteria is used
advantages of natural fertilisers
-they increase plant growth
-they improve yield
-they’re cheaper than artificial fertilisers
disadvantages of natural fertilisers
-they take time to make
-they are not all of the same quality
-large amounts are needed
advantages of artificial fertilisers
-they increase plant growth
-they improve yield
-only small amounts are needed
-they’re easy to use
disadvantages of artificial fertilisers
-they are easily washed away
-they have a negative effect on microorganisms
-they can effect soil structure
eutrophication
-excess nitrates run off into bodies of water
-this causes excess growth of alage on the surface of the water
-reduced light so aquatic plants die
-sapribionts respire aerobically while decomposing dead matter
-less oxygen for fish and other organisms so they die
ploughing optimising the nitrogen cycle
-the process of breaking and loosening the soil
-this increases air flow and hence there is more oxygen for aerobic respiration of nitrifying bacteria (which convert ammonia into nitrates)
-this increases yield as there are more nitrates available in the soil for the plants to grow
legumes optimising the nitrogen cycle
-they introduce nitrogen into the cycle, specifically ammonia and nitrates
-they increase soil fertility so the yield is increased
crop rotation optimising the nitrogen cycle
-it reduces anaerobic conditions so that less denitrification occurs
-this means that more oxidation occurs
-this increases the yield
nitrogen cycle
-nitrogen gas in the air is converted to ammonia in the soil by nitrogen fixing bacteria
-some nitrogen fixing bacteria in leguminous plant root nodules have a mutualistic relationship with plants and convert nitrogen gas into ammonia and nitrates
-nitrates in the soil are absorbed by plant roosts and converted into nitrogen containing compounds e.g. amino acids and DNA
-nitrogen containing compounds may be absorbed when eaten by consumers
-proteins from waste and dead material are broken down/ hydrolysed to ammonia in soil by enzymes released by saprobionts during ammonification
-ammonia in the soil is oxidised to nitrites, then nitrates by nitrifying bacteria in aerobic conditions
-if the soil is waterlogged, the lack of oxygen leads to denitrification where the nitrates are converted back to nitrogen gas by denitrifying bacteria
phosphorus cycle
-plants absorb phosphorus from the soil
-consumers eat the plants and absorb the phosphorus
-dead and waste material is decomposed, releasing phosphorus into the soil
-runoff from farm fertiliser means excess phosphorus enters bodies of water
-weathering releases phosphorus from the rock into the water and soil
-leeching of phosphorus from the soil/ weathered rock causes phosphorus to enter the water
