topic 4: ecology and the environment

• Individual


  Part of a species, lives in its habitat within a population
• Population


  Many different populations interact in the same habitat, creating a community
• Ecosystem


  Interaction of a community with non-living (abiotic) parts of the environment
• Investigating population size using quadrats

  1. Use quadrats to sample a transect area

  2. Count the number of organisms in each quadrat

  3. Estimate the total population size across the whole area
• Quadrats


  • Used to study ecology, make it easier to estimate distribution and abundance of organisms within a large area by looking at a few smaller representative samples
• Transect


  A defined area where the samples will be taken, used to estimate the number of the organism across the whole area
• Biodiversity


  A measure of the range of species living within an ecosystem
• Investigating biodiversity using quadrats

  1. Use quadrats to sample an area

  2. Count the populations of different species in each quadrat

  3. Measure the biodiversity of the area
• Abiotic factors


  • Light intensity
  • Temperature
  • Moisture levels
  • Soil pH and mineral content
• Biotic factors


  • Food availability
  • New predators
  • New pathogens
  • Competition
• Trophic levels


  • Producers
  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
  • Decomposers
• Food chain


  Shows the feeding relationships between organisms, organised by trophic levels
• Food web


  A collection of different food chains to show how all the organisms in the habitat interact, showing interdependence
• Pyramid of numbers


  Shows the population of each organism at each trophic level of food chain
• Pyramid of biomass


  Shows the relative dry mass of material at each trophic level
• Producers (e.g plants and algae) transfer about 1% of the incident energy from light for photosynthesis
• Only approximately 10% of the biomass of each trophic level is transferred to the next
• Carbon cycle


  1. Respiration

  2. Photosynthesis

  3. Decomposition

  4. Combustion
• Air pollutants


  • Sulfur dioxide
  • Carbon monoxide
• Greenhouse gases


  • Water vapour
  • Carbon dioxide
  • Nitrous oxide
  • Methane
  • CFC
• Effects of global warming include climate change, rising water levels, and loss of habitats
• Pollution of water by sewage

  1. Decomposers respire aerobically to break down sewage, using oxygen

  2. Algae bloom blocks light from reaching aquatic plants, causing them to die

  3. Oxygen depletion leads to death of other aquatic organisms
• Eutrophication


  When fertilisers are washed off from the land into nearby rivers and lakes, encouraging rapid growth of algae