Energy and Ecosystems

• Producer

  Primary source of biomass on earth, first trophic level in every ecosystem and they harness energy from the sun.
• Consumer


  Organisms that feed off other organisms, they do not produce their own food and are categorised into primary, secondary and tertiary.
• Saprobiont

  Organisms that digest their food externally and then absorb the products. e.g. Fungi and bacteria
• Herbivore


  Organism that is anatomically and physiologically adapted to eating plants.
• Carnivore


  Organism who eats by hunting other animals
• Omnivore


  Organism that has the ability to survive on both animal and plant matter.
• Ecosystem

  A natural biological unit that is made up of both biotic and abiotic factors.
• Community


  The population of all the species of plants and animals living in a particular area.
• Habitat


  An area or location where a species or community lives.
• Food web


  A network of interconnected food chains that shows the energy flow through part of an ecosystem
• Food Chain


  A list of organisms in a habitat that shows their feeding relationship.
• Ecological niche


  The role an organism plays within an ecosystem
• Biotic factor


  Living factors of an ecosystem
• Abiotic factor

  Non-living factors of an ecosystem
• Biomass


  The total quantity or weight of organisms in a given area
• What is the difference between fresh and dry biomass?

  Fresh includes water and dry does not include water
• What is the advantage of calculating fresh mass over dry mass?

  Doesn't kill the organism by drying it out.
• Disadvantage of calculating dry mass over fresh mass

  Dry mass does not include water content
• What is the unit for biomass?

  grams/ meter²
• Why are plants not very efficient at capturing light energy?

  1. Light may be wrong wavelength
  2. Light is reflected by waxy cuticle
  3. Light is used for water evaporation
  4. Over 90% of the sun's energy is reflected into space by clouds
  5. Light may not fall on a chlorophyll molecule
• Photosynthetic efficiency

  Photosynthetic efficiency = energy incorporated into plant biomass/ light energy falling onto plant
• Gross primary production


  The total quantity of chemical energy stored in plant biomass in a given area at a given time.
• Gross primary production(GPP)


  The total quantity of chemical energy stored in plant biomass in a given area at a given time.
• Net primary production

  Amount of chemical store left after respiration (NPP) NPP = GPP-R
• Secondary productivity


  The rate at which energy is used to make new organic molecules within heterotrophs (an organism that cannot make its own food)
• Trophic efficiency

  The transfer of energy from one organism to another (trophic levels) is inefficient. Efficiency = energy available after transfer / energy available before transfer x 100 (KJm-2 year-1)
• Why is there such a low % of energy transferred at each stage of a food chain?

  1. Some organisms cannot be eaten
  2. Once eaten, some organisms cannot be digested
  3. Energy is lost in excretory materials e.g. urine
  4. Energy is lost in the form of heat from respiration
• Carnivores are more efficient at energy conversion than herbivores as they can digest and reabsorb more of their high protein diets
• Farming methods and how they are made more efficient

  1. Growing crops by hydroponics - a method of growing plants without soil indoors. Allows farmers to control temperatures and light levels to improve plant production.
  2. Growing crops in greenhouses - Farmers can control climate inside to increase crop yield e.g. higher concentrations of co2 which increases photosynthesis and reduces transpiration.
  3. Fish farming - large scale fishing with larger nets.
  4. Battery farming of animals - Breeding a large number of animals in a confined space allow farmers to control temperature and food intake.