energy transfers and the nutrient cycle Flashcards
what is an ecosystem
an ecosystem is a form of biological community containing all living and non-living factors
what do all organisms require
all living organisms require energy to live for various processes e.g. some organisms obtain energy from the sun (plants) and some from consuming other organisms
what is organisms use energy for
energy is used (and CO2) to synthesise organic compounds
e.g. in plants most sugars synthesised by plants are used as respiratory substances, the rest are used to form other biological molecules e.g. lipids
These molecules form the biomass
how is biomass measured
it is measured in terms of carbon or dry mass of tissue per given area
Or
chemical energy store in dry biomass which is measured using calorimetry.
how does calorimetry work
chemical energy store in dry biomass which is measured using calorimetry.
The amount of heat given off tells you how much energy is in it. Energy is measured in joules (J) or kilojoules (kJ).
A sample of dry biomass is burnt and the energy is used to heat to heat a known volume of water.
The change in temperature is used to calculate the chemical energy of the dry biomass
what do food chains consist of
food chains consists of many trophic levels
how does energy pass through food chains
energy is transferred throughout these trophic levels
Energy is lost throughout the food chain through process like respiration, excretion of faeces and urine
how do we work out energy efficiency
net production of trophic level / net production of previous trophic level x 100
how do we measure energy loss
net primary production (NPP)
net production
how do we measure energy loss in plants
NPP = GPP-R
is is mainly used for plant forwth an reproduction because it does not take into accoint energy losses due to excretion and urine.
However it is available for herbivores and decomposes as they mainly obtain their energy via producers
what is GPP
we can use via gross production (GPP) which is the chemical energy store in PLANTS’ biomass, in a given area or volume
what is NPP
After knowing the GPP we can measure the NPP (net primary production)
which is the chemcial energy store in plant biomass AFTER RESPIRATORY LOSSES to the environment
what is net production
net production is used for consumers higher up the tropic level
we use this equation: N = I -(F+R)
I= Chemical energy store in injested food
F= Chemical energy lost to the environment in faeces and urine
R= respiriroy losses to the environment
how do we measure the RATE of primary and secondary production can be measured
the rate of primary/ secondary production is called primary/ secondary PRODUCTIVITY
This measured as biomass in a given area per time
it is a good way to measure primary and secondary production as it often changes with seasons
why are nutrients important
nutrients are recycled within natural ecosystems in order to build important organic materials e.g. DNA
what microoganisms recycle chemical elements
the main microorganisms are saprobiants
saprobiants are organisms that digest their food EXTERNALLY and then ABSORB THE PRODUCTS
e,g, fungi
what are mycorrhizzae
they are fungal “associations” or a connection between plant roots and fungi
Mycorrhizae provide a large surface area for the uptake of water and inorganic ions
They act like a sponge so they can absorb and absorb and hold water and minerals
what is the relationship between plants and fungi
the relationship between plants and fungi are mutualistic/ symbiotic
as the plant provides the fungi with carbohydrates while the fungi provides the plant inorganic ions/ water
what are the stages of the nitrogen cycle
- nitrogen - fixation
- ammonification
- nitrification
- denitrification
what happens in nitrogen fixation
- nitrogen fixing bacteria converts atmospheric nitrogen to ammonium ions
the nitrogen fixing bacteria are either free - living in the soil or have a mutualistic relationship with legumious plants e.g. clovers and beans as they can live in their ROOT NODULES
what is ammonification
- ammonium ions in ammonification are produced from organic nitrogen e.g. decomposition of proteins, DNA, urea e.t.c are converted to ammonium ions which are released into the soil
- this is carried out by saprrobiants: bacteria and fungi that can digest waste externally
what happens in nitrification
- ammonium ions in the soil (produced via ammonification and nitrogen fixation) are oxidised to nitrites then nitrates by nitrifying bacteria
this is a two stage oxidation reaction
what happens in denitrification
- it converts nitrogen in compounds back to nitrogen gas
- denitrification is not a useful process as nitrogen gas cannot be absorbed by plants
It is carried out by Anaerobic denitrifying bacteria which iswh farmers aerate their soil so denitrification is limited
what happens in the phosphorus cycle
- environmental conditions e.g. erosion and weathering causes the release of phosphate ions by rocks into soil and bodies of water
- plants assimilate (take in) these phosphate ions the phosphate ions are used by plants to sythesise DNA e.t.c
- animals eat the plants and use the ions to sythesise organic materials
- animals die and decompose returining the phosphate to the soil
- bacteria (sapriobiants) in the soul break down phosphate into inorganic form (mineralisation)
- inorganic forms of phosphorus can end up in water via rainfall again and be assimilated by plants
what are fertillisers
fertilisers replace the nitrates and phosphates lost by harvesting plants and removing livestock
there are two types of fertilisers:
-natural
-artificial
what are the advantages of natural fertilisers
- cheaper and free if it comes from your own livestock
what are the advantages of artificial fertilisers
- contains the exact amount of minerals
2. more water-soluble so high absorption of inorganic ions
what are the disadvantages of using artificial fertilizers
it can lead to leaching and eutrophication
what is leaching
leaching is when water-soluble compounds are washed away into bodies of water
e.g. rivers and ponds
what is the process of eutrophication
- leached nitrates in bodies of water cause algae growth on the surface
- excess algae growth blocks light, so plants the surface can’t photosynthesise and therefore die
- aerobic bacteria feed on plant matter and response, using the O2 up in the water
- Fish and other aquatic organisms die due to lack of O2
