Classification and biodiversity

• Adaptations


  Morphological and behavioural changes that organisms develop to help them survive in their environment
• Resources organisms obtain from their environment

  • Food
  • Water
  • Minerals (for plants)
• Some resources may be limited in supply, leading to competition between organisms to obtain them
• Population size can be reduced by disease, pollution, and competition for limited resources
• Biodiversity


  The variety of different species, and numbers within those species, in an area
• Measuring biodiversity


  1. Use transects and quadrats

  2. Place quadrats at regular intervals along transect

  3. Record numbers and types of organisms in quadrats

  4. Analyse data to look for relationships and distribution patterns
• Obtaining valid data


  • Use appropriate apparatus
  • Take sufficient sample size
  • Take repeat measurements
  • Use regular or random sampling points
  • Collect sufficient data to draw valid conclusions
• Capture-recapture technique


  • Used to estimate population size of mobile organisms
  • Involves capturing, marking, and releasing a sample, then recapturing a second sample to calculate total population
• Stable ecosystems generally have higher biodiversity
• Benefits of high biodiversity

  • Help regulate atmosphere, water supply, nutrient cycles, and soil fertility
  • Provide potential food, industrial, and medical resources
• Threats to biodiversity


  • Changes in land use (e.g. farming, deforestation, quarrying)
  • Climate change
  • Over-exploitation (e.g. overfishing, hunting)
  • Invasive alien species
• Computer programs can be used to make predictions about population numbers and the effects of human activity, to help avert future problems
• Biological control


  The use of natural predators to limit, control or remove a pest, as opposed to using chemical control (pesticides)
• Advantages of biological control

  • No chemicals used, so no pollution/bioaccumulation
  • Carefully selected organism attacks just the pest and nothing else, so more selective
  • Pest population reduced to manageable levels, not completely wiped out, so ecosystem more stable
• Disadvantages of biological control

  • More complicated to operate than chemicals, so can be more expensive
  • Difficult to use outdoors as control organisms may migrate, so best used in greenhouses
  • Biological control agent may cause other problems in the ecosystem
• Modern biological control uses detailed research and trials to learn about the control agents, reducing problems with introducing alien species