Energy and ecosystems
- Created by: Trudy
- Created on: 24-11-13 21:25
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- Energy and ecosystems
- Food chains and foodwebs
- Producers
- Organism that synthesises organic molecules from simple inorganic ones.
- 6CO2+6H2O=light energy+C6H12O6+6O2
- Consumers
- Any organism that obtains energy by 'eating' another
- Decomposers
- A group of organisms that break down comples material into simple components again releasing valuable minerals which cane be absorbed by plants.
- Detritivores e.g. earthworms
- Decompsors e.g. fungi and bacteria
- Food chains
- Describes a feeding relationship in which the producers are eaten by primary consumers....
- Trophic level
- The postion of an organism in a foodchain
- Producers
- Energy transfer between trophic levels
- Suns energy
- Reflected back into space
- not all wavelenghts are absorbed and used for PS
- light may not fall on a chlorophyll molecule
- a factor may limit rate of PS
- Net production=gross production-respiratory loss
- Gross production
- Total quantity of energy that the plants in a community convert to organic matter
- some of the organism isn't eaten
- Faeces
- Exretary materials (urine)
- Respiration
- Mammals and birds because they need to maintain high body temperture
- Gross production
- Relative inefficency of energy transfer between trophic levels explain why:
- food chains mostly consisting of 4-5 trophic levels
- Total mass of organismsin a paticular place (biomass) is less at higher trophic levels
- total amount of energy stored is less at each level as one moves up a food chain
- Calculating efficency of energy transferr
- = energy available after transfer/energy available before the transfer x 100
- Suns energy
- Ecological pyramids
- Number
- no account is taken for size
- number of individuals can be so great that its impossible to represent them accurately
- Biomass
- the total mass of the plants/animals in a particular place
- fresh mass
- water makes it unreliable
- dry mass
- animal needs to be dead
- small samples= unrepresentative
- grams per meter squared/cubed (if a volume
- Energy
- most accurate
- collected in a given area, set period of time
- kJm-2year-1
- organisms of the same dry mass may store different amounts of energy
- Number
- Agricultural ecosystem
- trys to ensure much of the available energy from the sun is transferred to humans
- Suns energy
- Reflected back into space
- not all wavelenghts are absorbed and used for PS
- light may not fall on a chlorophyll molecule
- a factor may limit rate of PS
- Suns energy
- Productivity
- rate at which something is produced
- Net productivity=gross productivity-respiratory loss
- net productivity
- efficiency of crop carrying out PS
- area of ground covered by the leaves of the crop
- energy input
- food
- fossil fuels
- prevent climax community
- trys to ensure much of the available energy from the sun is transferred to humans
- pesticides
- poisonous chemicals that kill pests
- specific
- biodegrade
- cost effective
- not accumulate
- biological
- specific
- control organism can reproduce itself
- pests dont become resistant
- chemcial
- effecct on non-target species
- must be re-applied (expensive)
- resistance
- integrated pest control
- emphasis on acceptable level of pest
- animal or plant varieties that suit local area and pest resistant as possible
- suitable habitats close to crops for natural predators
- monitoring crop for signs of pests
- removing pests by hand
- using biological agents
- using pesticides as a last resort
- intensive rearing of domestic live stock
- restricted movement
- warm enviroment
- controlled feeding
- predators are excluded
- selective breeding
- growth hormones
- Food chains and foodwebs
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