23.1-2 Ecosystems and energy flow

• Define the term 'abiotic factor'

  any non-living factor e.g. sunlight
• Define the term 'biotic factor'

  any living factor e.g. predators
• Give 3 examples of abiotic factors

  temperature, light, pH, water, humidity, oxygen availability, edaphic(soil) factors
• Give 3 examples of biotic factors

  Competition, food, territory, breeding partners, predators
• Describe the importance of soil for plants

  Soil provides minerals for growth, water for photosynthesis, anchorage for roots
• Explain how particle size affects the air content and permeability of soils

  small particles - few air spaces, retains water and floods easily eg. clay

  large particles - lots of air spaces, does not retain water eg. sand
• Define the term ecosystem

  Made up of all the living organims that interact with one another in a defined area and also the physical factors present in that region eg. rock pool
• Define the term producer

  Producer - makes its' own food, usually by photosynthesis to produce biomass ( inlcudes algae and plankton)
• Define the term carnivore

  Eats only other animals
• Define the term herbivore

  Eats only plants
• Define the term Omnivore

  Eats both plants and animals
• Define the term primary consumer

  Eats producers, usually a herbivore
• Define the term secondary consumer

  Eats primary consumers, usually an omnivore
• Define the term tertiary consumer

  Eats a secondary consumer
• Define the term trophic level

  Trophic level - position or stage that something occupies in a food chain
• Define the term biomass

  The mass of living material present in a particular place or in particular organisms
• How do you find the dry mass of an organism?

  Organism has to be killed and put in an oven to evaporate the water
• How do you calculate the net production of biomass made by a primary producer?

  Net production = gross production – respiratory losses
• Why can't plants use all of the sunlight that hits them?

  Some parts of a plant do not photosynthesise, some light passes through, some is the wrong wavelength
• Why isn't all energy transferred to the next trophic level?

  Some parts of an organism are not digested, some parts are not eaten e.g. bones, some is used up for energy for movement/ respiration (respiratory losses)
• approximately what % of energy is passed to the next trophic level

  10%
• How do you calculate % efficiency of energy transfer?

  Net productivity of energy transfer of trophic level/ next productivity of previous trophic level x 100
• What is the role of a herbicide?

  Kills weeds that compete with crops - reduces competition
• What is the role of a fungicide?

  Kills fungal infections that damage crops
• What is the role of an insecticide?

  Kills insect pests that damage and eat crops
• What is the role of fertiliser?

  A chemical that provides crops with the minerals required for growth
• Why is intensive farming beneficial?

  Controls living conditions for organisms so that more energy is put in to growing e.g. animals are kept warm and move around less
• Define the term ecosystem

  Self-contained unit in ecology made up of biotic and abiotic factors
• Define the term Community

  All the populations of different species living and interacting with each other in a particular area