energy and ecosystems

• detritovore are animals that consume dead matter like worms to increase surface area for saprobionts to work
• saprobionts are decomposers that secrete enzymes or chemicals to break down matter and carryout extracellular digestion. examples are fungi and bacteria
• biomass is the total mass of living material in a specific area at a given time
• fresh biomass is the mass of living material containing water
• dry biomass is the mass of living material which has no water
• measure biomass using dry mass but you have to kill the organism
• you can calculate chemical energy of biomass with a bomb calorimeter
• bomb calorimeter

  • a sample of dry mass is weighed and burnt in a container in pure oxygen in a sealed container
  • the bomb is surrounded by water and temperature rise is recorded
  • we know the specific heat capacity of water so we can calculate energy released from burnt mass
• organisms can be divided into 3 groups depending on how they obtain their energy

  • producer
  • heterotroph
  • saprobiont
• producers are photosynthetic organisms that manufacture organic substances using light energy, water and CO2
• heterotrophs obtain there energy by consuming other organisms. primary consumers feed directly off producers. secondary consumers and tertiary consumers are usually predators
• each stage of a food chain is known as a trophic level
• a food web shows the feeding relationships between a community because an organism may eat multiple different species that others also eat
• gross primary production is the total quantity of energy that the plants in the community convert to organic matter
• net primary production is the energy the plant stores as biomass
• gross production - respiratory loss = net production
• secondary productivity is the rate at which energy is used to make new organic molecules within heterotrophs
• trophic efficiency = energy available after transfer/ energy available before transfer all X 100