GCSE AQA Biology 1 Energy Transfer, Decay and The Carbon Cycle

GCSE AQA Biology 1 Energy Transfer, Decay and The Carbon Cycle

1. Pyramids of Biomass

   • Biomass: Mass of living material
   • Less energy/biomass as you go up trophic levels
   • Mostly pyramid-shaped
     • Producer at the bottom

2. Energy Transfer

   • Energy from Sun - source of energy for life
     • Light energy converted to chemical energy
   • Green plants use small % of light in photosynthesis
     • Energy stored in cells - animals eat them
   • Respiration supplies energy for movement
     • Energy lost to surroundings as heat
       • Especially in mammals and birds - have to keep body at constant temp.
   • Some material is inedible and some is lost as waste
   • Hardly any food chains more than 5 levels
     • Because so much energy is lost. Therefore, there is not enough left to support more organisms

3. Decay

   • Plants take in elements and pass through food chain
     • Like carbon, oxygen, hydrogen and nitrogen
     • Elements returned in waste products or when they die
       • Materials decay - broken down by microorganisms
         • Elements return to soil
   • Microorganisms work best in warm & moist conditions with oxygen
     • Composting
       • Benefits
         • Recycles minerals & nutrients
         • Reduces landfill
         • Reduces production of methane

4. The Carbon Cycle

   • Only 1 arrow coming down - photosynthesis
     • Carbon dioxide is removed from atmosphere by green plants, some of the carbon is used to make carbohydrates, fats and proteins in the plants
   • Some carbon returned as carbon dioxide - respiration
     • Some carbon moves through food chain to animals
   • When plants/animals die, detritus feeders and microorganisms feed on remains
     • These organisms respire
   • Animals produce waste
     • Broken down by detritus feeders and microorganisms
   • Useful plant/animal products are burnt (combustion) - releasing carbon dioxide

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