Ecology

• Define habitat


  The place where an organism lives
• Define population

  All the organisms of one species living in a habitat
• Define community

  The populations of different species living in a habitat
• Define ecosystem

  The interaction of a community of living organisms with the non-living part of the environment
• Define biodiversity


  The variety of different species within an ecosystem

  - measure of richness and evenness
• High biodiversity


  Lots of different species which show a lot of variation (rich), and evenly distributed
• Compare difference in biodiversity

  - "both areas have the — number of species"

  - "area — has higher species evenness"
• Define abiotic factors and give examples

  Non-living

  -temperature

  -light intensity

  -CO2 levels
• Define biotic factors and give examples

  Living

  - competition
• How does competition affect population of species

  One is better adapted to use the resources, so it will outcompete the less adapted species until there are too few members of the less adapted species to breed
• How does desperate in abiotic factors affect population growth?

  Decrease the rate of photosynthesis and decrease plant growth
• How do producers get their energy?


  Convert light energy from sun into chemical energy during photosynthesis
• Define food chain


  Transfer of energy from one organism to the next
• Not all energy is transferred to the next trophic level - why?

  - not all parts consumed (bones)

  - not all material digested/absorbed

  - energy used to generate heat for movement

  - lost in waste as urine

  - lost in respiration as C02 and water
• Define interdependence


  Organisms depending on each other for survival
• Describe 2 ways in which acid rain is formed

  1. Combustion of fossil fuels releases sulfur dioxide (and nitrogen oxide) which reacts with oxygen air and dissolves in rainwater to produce sulfuric and nitric acid which cause acid rain.

  
  

  2. Sulfur dioxide and nitrogen oxide released from vehicles and factory chimneys react with rainwater
• How does acid rain cause problems?

  - Inhibits plant growth by damaging leaves, flowers, tree roots

  - Corrodes stone buildings

  - makes lakes and rivers too acidic, killing aquatic animals
• What are the greenhouse gases?

  Carbon dioxide

  Water vapour

  Nitrous oxide

  Methane

  CFCs
• Examples of human activity that cause global warming

  - deforestation: carbon stored in trees is released

  - burning fossil fuels: release CO2

  - increase livestock farming: cattle produce methane as they digest grass
• How does global warming occur?


  Greenhouse gases trap the sun's heat and stop is leaking into space to prevent the earth getting too cold.

  With an abundance of it, the earth would become too warm
• Consequences of global warming

  - increased ocean temperatures causes ice caps/glaciers to melt, leading to high ocean level and flooding

  - extreme weather: changes in/loss of habitat

  - increasing temps: decrease in biodiversity, food chains disrupted
• Effects of deforestation

  - disturbs water cycle: lack of trees, no evapotranspiration of rainwater

  - flooding: without trees, the topsoil is loose and easily washed away by rain, increasing risk of flooding

  - when trees are burnt, co2 is released, causing global warming

  - cutting down trees means less co2 taken in, and less oxygen released.
• How does water polluted by fertilizers cause ecosystems to die?

  Fertilizers increase the growth of algae and water plants

  Algal bloom on the surface blocks sunlight, so water plants at the bottom die

  Bacteria decomposes dead plants and algae, using and reducing oxygen content in water

  Organisms die
• How does water polluted by sewage cause ecosystems to die?


  Sewage is a good source of food for bacteria, which increase rapidly

  Deplete oxygen in water

  Organisms die
• how can overfishing managed

  • fishing quotas - limits on the number anf size of fish that can be caught in certain areas
  • net size - limits of the mesh size of the fish net, to reduce the number of unwanted fish caught.
• techniques used in fish farming to increase yields

  • maintenance of water quality: water is filtered to remove waste and harmful bacteria to prevent diseases and maintain high levels o oxygen for aerobic respiration
  • Protective nets to reduce interspecific predation (predation between different species): different species of fish are separated by fences, nets, tanks to prevent fighting.
  • Separated by size and age to control infraspecific predation (between same species)
  • Antibiotics - to prevent disease
  • Kept in small numbers - minimize spread of diseases
• how to control overfishing

  • limits on number and size of fish that can be caught in certain areas
  • limits of the mesh size of the fish net, reduces number of unwanted fish caught