FOOD CHAINS AND ENERGY TRANSFER

• WHAT ARE THE THREE GROUPS OF ORGANISMS?

  producers, consumers, saprobionts
• PRODUCERS?

  • photosynthetic organisms
  • plants, algae, plankton (protists)
• CONSUMERS?

  • obtain energy by feeding on other organisms
  • usually predators
  • can be scavengers or parasites
• SAPROBIONTS?

  • decomposers
  • break down complex material in dead organisms
  • into simple ones
  • include fungi and bacteria
• BIOMASS?

  total mass of living material in a specific area at a given time
• UNITS OF BIOMASS?

  gcm^-2 or gcm^-3
• HOW IS BIOMASS MEASURED?

  dry
• HOW TO FIND DRY BIOMASS?

  1. Heat tissue in oven to evaporate water
  2. Record mass at regular intervals
  3. Stop heating when mass is constant
• HOW TO CALCULATE ENERGY IN BIOMASS?

  bomb calorimetry
• BOMB CALORIMETRY?

  1. Sample of dry material weighed
  2. Burnt in pure oxygen
  3. Within sealed chamber (bomb)
  4. Surrounded by water bath
  5. Heat causes rise in temperature
  6. Can calculate energy released using specific heat capacity of water, volume of water and temperature change