Energy and ecosystems 2

  • Created by: Hindleyc
  • Created on: 11-12-18 20:39
What is secondary production?
Rate at energy used to make new organic molecules within heterotrophs
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Sun (energy) to autotrophs=
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Organism (energy) to next organism=
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What is the eqn for efficiency of chemical potential energy transferred between trophic levels
energy available after transfer/ energy available before transfer x 100
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What happens between trophic levels
large % of energy lost
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Some of organism cannot be eaten eg bones, fur plant- bark/roots branches. Once eaten some of organism cannot be digested (feathers, fur) no useful energy from it- plants-cellulose). Energy is lost in excretory materials, such as urine eg faeces.
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How else
Energy lost in form of heat from resp and body heat - endotherm warm blooded
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How is more efficient
smaller- less energy lost through excretion and egestion v little energy req for movement and reproduction
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Reduced energy available =
reduced efficiency
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Top consumer has
Little energy left up trophic level
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What is energy not
Lost from ecosystem- not whole ecosystem as would be gone, just organism
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What is maximising productivity trying to do?
inc 2%- max amount of energy transferred from solar energy to humans
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How to improve pp
Remove factors that inhibit plant growth, such as predators and disease (herbicides , pesticides etc barrier greenhouse). Use antibiotics. Improve conditions for p/s by inc light, water co2, conc, temp, and available nutrients optimum level
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how else
Inc ground coverage- allows max amount of available energy from sun to be used
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Energy input=
only source of energy in natural ecosystem = sun
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What require an additional input of energy to maintain ideal conditions?
Agricultural ecosystems
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how is energy supplied in which 2 diff forms?
Food- energy in manual labour involved in farming is provided by food. Fossil fuels - mechanical engineering needed for ploughing harvesting transport etc, often supplied by FF, heat energy from FF is also used to maintain ideal temp for p/s greenhou
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How can farming practice inc yield?
by inc efficiency of energy transfer along food chain which produces our food- as energy passes along food chain only small % passes from 1 organism to next - much energy lost as heat during resp
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What any practice to reduce R loss in human food chain do?
decrease energy loss and inc yield
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Intensive rearing of domestic livestock - convert smallest possible quantity of food energy to greatest quantity of animal mass
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What does this do?
Minimise energy losses from domestic animals during lifetime
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What will this do?
More food energy taken in by animals will be converted into body mass, ready to be passed on to next link in food chain -us
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How can energy conversion be made more efficient?
Ensuring as much energy from resp as possible goes into growth rather than other activities or other organisms
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Keep organisms in confined spaces eg small enclosures barns or cages- factory farming
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Why does this inc energy conversion rate?
Movement restricted and so less energy is used in muscle contraction, Environment can be kept warm in order to reduce heat loss from the body (most intensively reared species are warm blooded).
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Feeding can be controlled so that the animals receives the optimum amount and type of food for max growth with no wastage. predators excluded so that there is no loss to other organisms in the food web
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What is another farming practice that inc the efficiency transfer ?
Reduce losses to non-human food chains by simplifying food webs- reduce or eliminate organisms that are part of a food web and which compete with the plant or animal that is being farmed.
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What do weeds compete with crops for? what are these often in
water mineral ions co2 space light- often in limited supply
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What does nay amount taken in by the pest mean?
less available for crop plant
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What may insect pests do
damage leaves of crop limiting photosynthesis ability thus reducing their productivity
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what else alternatively
in direct competition with humans eating crop itself
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What are many crops now grown in. what doe this do?
Monoculture enables insect and fungal pests to spread rapidly
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What may pests of domesticated animals cause?
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What may the animal then not do?
Grow as rapidly - be unfit for human consumption or die- all of which lead to reduction in productivity
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What the aim pest control
simplify food webs and so limit the effect of pests on productivity to a commercially acceptable level= balance cost of pest control with benefits it brings
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2 diff interests involved - farmer who has to satisfy our demand for cheap food while still making a living and the conservation of natural resources which will able us to continue to have food in the future
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what is the trick
- balance these 2 often conflicting interests
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How to inc growth of crops
use fertilisers, pest control, fungicides, monoculture, crop rotation,
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rearing livestock
restrict movement, control environmental temp, control food intake protect from predators
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Card 2


Sun (energy) to autotrophs=



Card 3


Organism (energy) to next organism=


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Card 4


What is the eqn for efficiency of chemical potential energy transferred between trophic levels


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Card 5


What happens between trophic levels


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