Biomass, Food Chains and Nutrient Cycling

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  • Created by: Rebecca
  • Created on: 01-05-11 13:52

Define Biomass:

The amount of living things at each trophic level of the food chain.

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How is energy lost?

  • Movement: muscle contractions use energy
  • Maintaining a constant body temperature: only in warm-blooded animals i.e. mammals and birds
  • Faeces and Urine: energy is lost in products that aren't absorbed into the body.

Remember: not all food can be digested e.g. fur, bones etc.

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Describe the process of decay:

  • Living things are broken down/digested by microorganisms
  • Detritivores actually eat the organic matter (like earthworms) 
  • Decomposers secrete enzymes to digest the organic matter and then absorb the resulting molecules (like bacteria or fungi).

Both need:

  • Warmth
  • Moisture
  • Oxygen

The more of the above that are available, the quicker the decay process happens.

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How can you improve food production efficiency?

  • Reduce number of trophic levels

Energy is lost at each stage of the food chain through movement, heat and excrement so only a small percentage is used to make new cells. The fewer trophic levels, the less energy is lost so it's cheaper to produce the same quanitity of food.

  • Reduce energy loss at each trophic level

Reducing heat loss and movement of animals be be achieved by keeping them close together in cages. This restricts movement and keeps them warmer so food can be produced more cheaply as less food is needed to feed the animals.

HOWEVER, this raises problems due to animal rights and also the spread of disease. It's easier for pathogens to pass in a crowded environment so animals may have to be immunised. If humans eat these antibiotics then bacteria in humans may become resistant, resulting in illness.Heating can also increase costs, produce CO2 and use fossil fuels.

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The Carbon Cycle

(http://www.google.co.uk/imgres?imgurl=http://www.windows2universe.org/earth/climate/images/carboncycle.jpg&imgrefurl=http://www.windows2universe.org/earth/climate/images/carboncycle_jpg_image.html&usg=__ykX9d-Yti_qFrFj-iv5JZFSidnc=&h=720&w=720&sz=187&hl=en&start=0&sig2=CxVTaYzRR25bPOICNl-NVQ&zoom=1&tbnid=Ro3WYvi1L_RGrM:&tbnh=111&tbnw=111&ei=hWW9TfqUFIWo8QPO5fjEBg&prev=/search%3Fq%3Dsimple%2Bcarbon%2Bcycle%2Bdiagram%26um%3D1%26hl%3Den%26sa%3DX%26rlz%3D1R2GGLL_en%26biw%3D851%26bih%3D484%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=273&vpy=48&dur=2506&hovh=225&hovw=225&tx=119&ty=117&page=1&ndsp=12&ved=1t:429,r:1,s:0)

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