Energy Transfer and nutrient cycles

What is an ecosystem?
The entire number of organisms in an area and all the abiotic conditions
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What must ecosystems contain?
Producers that make their own food which start the food webs.
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How is biomass measured?
By the carbon or dry mass of an organism.
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How can this be done?
Removing the water through heating or calorimetry.
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What is calorimetry?
measures the amound of chemical energy an organism contains; the organism is burnt which releases the energy as heat, heating a known volume of water- the temperature change of the water can be used to calculate the chemical energy of the biomass.
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What is Gross primary production (GPP)
The amount of chemical energy converted from light energy by plants in a given area or time.
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What is respiratory loss?
The loss of GPP lost to the environment as the plant respires, usually about 50%
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What is the remaining energy known as?
Net primary production (NPP)
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What is the equation of primary production?
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What is net production in consumers?
The energy left after a consumer has digested and used what energy they can / the energy for the next trophic level.
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What is the equation for this?
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What is I?
chemical energy in ingested food.
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What is F?
chemical energy lost in faeces and urine.
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What is R?
Respiratory losses.
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How would you calculate efficiency of energy transfer?
(net production of trophic level / net production of previous level ) x 100
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How could you increase efficiency?
Simplify food webs by having fewer organisms in the web means more energy for crops/livestock.
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How would reducing respiratory loss increase efficiency?
controlling the conditions livestock live in so more energy is used for growth and less is lost through respiration e.g restricting animals movements by keeping them in pens. This raises ethical issues about animal welfare.
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What does MYCORRHIZAE do?
Forms a symbiotic relationship with the roots of plants. They connect to the roots which increases the SA and helps plant absorb minerals which are scarce such as phosphorus.
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How does this benefit the fungi?
In return they obtain organic compounds from the plant, eg glucose.
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What is nitrogen fixation?
when nitrogen gas in the atmosphere is turned into nitrogen containing compounds e.g ammonia which can then be used in the plants to make proteins.
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What is ammonification?
nitrogen compounds in dead organisms are converted into ammonia/ ammonium ions by saprobiants.
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What is a saprobiant?
Saprobionts are organisms that digest their food externally and then absorb the products. Fungi are examples of saprobiontic organisms also known as decomposers.
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What is nitrification?
ammonia and ammonium ions in the soil are changed into nitrogen compounds that can be used by the plant.
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What is denitrification?
nitrates in the soil are converted into nitrogen gas by denitrifying bacteria- they use nitrates in the soil to resire, producing nitrogen gas- happens in anaerobic conditions e.g waterlogged soil.
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What is the 1st stage of phosphorus cycle?
Rocks are weathered which release Phosphate ions into the soil as well as leeching.
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What is the 2nd stage of phosphorus cycle?
Plants absorb the phosphate ions from their roots in the soil- Mycorrhizae increase the rate at which phosphates can be absorbed
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What is the 3rd stage of phosphorus cycle?
Phosphate ions are transferred through the food chains as animals eat other animals
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What is the 4th stage of phosphorus cycle?
Phosphate ions are lost through animal waste
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What is the 5th stage of phosphorus cycle?
Animals die and saprobionts break down the organic compounds releasing Phosphate ions into the soil and back to sedimentary rock.
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What is the 1st stage of Eutrophication?
mineral ions leached from the fertilized fields stimulate the rapid growth of algae in a pond
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What is the 2nd stage of Eutrophication?
the mass of algae blocks sunlight from penetrating the water
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What is the 3rd stage of Eutrophication?
plants die at the bottom of the water as they have no sunlight to photosynthesise with
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What is the 4th stage of Eutrophication?
bacteria feed on the dead organisms, increasing the number of bacteria.
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What is the 5th stage of Eutrophication?
Mass of bacteria reduced the oxygen content of the water by aerobically respiring
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What is the 6th stage of Eutrophication?
fish and other aquatic organisms die due to lack of oxygen.
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What effect does the respiring bacteria have?
Makes the water toxic with the CO2 from aerobic respiration.
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Other cards in this set

Card 2


What must ecosystems contain?


Producers that make their own food which start the food webs.

Card 3


How is biomass measured?


Preview of the front of card 3

Card 4


How can this be done?


Preview of the front of card 4

Card 5


What is calorimetry?


Preview of the front of card 5
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