Material cycling: Ecology: Biology: GCSE (9:1)

• Material cycling


  Many different materials cycle through the abiotic and biotic components of an ecosystem
• Water cycle


  Provides fresh water for plants and animals on land before draining into the seas, water is continuously evaporated and precipitated

  
• Evaporation

  Water evaporates from the sea into water vapour in the air, due to energy from the sun

  
• Condensation


  Water vapour eventually cools and condenses to form clouds of fresh water droplets

  
• Precipitation


  When many water droplets combine following condensation, precipitation of fresh water can occur as rain, hail, sleet or snow

  
• Streams and rivers


  Water from rainfall can travel down streams and rivers, before returning to the sea

  
• Aquifer

  An underground layer of water-bearing permeable rock, following the process of percolation where water filters through rocks and sediment

  
• Reservoir


  An artificial or natural lake where water is stored

  
• Transpiration

  Water enters plants through the roots and travels up the stem via the xylem to the leaves, where it transpires and evaporates

  
• Water in animals

  Animals consume water by drinking from water sources or consuming other organisms, water can then be removed via exhalation, urination or excretion as faeces

  
• Carbon cycle


  Returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants for photosynthesis

  
• Photosynthesis


  Plants store carbon from the atmosphere by converting carbon dioxide into glucose via the process of photosynthesis

  
• Carbon in plants

  Glucose in plants can be converted into complex carbon-based molecules such as carbohydrates and proteins, which can be passed on to animals that consume these plants

  
• Carbon in animals

  Animals obtain carbon by consuming plants and other animals, the carbon is stored as complex molecules such as carbohydrates, lipids and proteins

  
• Respiration

  Organisms can respire to release energy from glucose, which returns carbon to the atmosphere as carbon dioxide

  
• Excretion of carbon

  Animals can remove carbon via excretion of faeces and urea in urine or as methane gas that enters the atmosphere

  
• Decomposition


  Animals, plants and waste products are typically broken down by microorganisms, assuming the conditions for decay are available

  
• Microorganisms

  Microscopic organisms such as bacteria and fungi that are capable of cycling materials through an ecosystem such as nitrogen and carbon

  
• The cycling of materials by microorganisms

  Microorganisms can decompose organic material from dead organisms and return mineral ions to the soil or return carbon to the atmosphere as carbon dioxide

  
• Decomposer


  An organism such as bacteria or fungi that is responsible for the decay and breakdown of other dead organisms, so that important nutrients can be recycled

  
• Fossilisation


  Organisms that do not decay may fossilise and lock up or fix carbon in sedimentary rocks

  
• Combustion

  Coal, oil and natural gas are products of fossilised organisms that can be burned as a fuel source, which releases stored carbon back into the atmosphere as very large amounts of carbon dioxide