Ecology

• Levels of organisation in an ecosystem

  • Individual
  • Population
  • Community
  • Ecosystem
• Ecosystem


  The interaction between the living components and non-living components
• Factors that plants may compete for

  • Light
  • Space
  • Water
  • Mineral ions from soil
• Factors that animals might compete for

  • Food
  • Mates
  • Territory
• Intraspecific competition


  Competition within a species
• Interspecific competition


  Competition between different species
• Interdependence


  Different species in an ecosystem depend on each other for various resources, if one species is removed, the whole community may be affected
• Stable community


  A community in which all the biotic factors (the different species) and all abiotic factors are balanced so that population sizes remain relatively constant
• Abiotic factors


  Non-living factors
• Abiotic factors that may affect an ecosystem

  • Light intensity
  • Temperature
  • Moisture
  • Soil pH and mineral content
  • Wind intensity and direction
  • Carbon dioxide level
  • Oxygen level
• Light intensity affects an ecosystem


  Different species of plants may have different optimum light intensities for growth
• Temperature affects an ecosystem


  Different species of plants and animals may have different optimum temperatures for growth and survival
• Soil pH affects an ecosystem

  • Certain plants may grow better in either alkaline or acidic soil
  • Soil pH may affect the appearance of the plant eg. colour of hydrangea
• Moisture level affects an ecosystem

  • Many plants cannot survive in waterlogged soil as their roots cannot respire
  • Certain plants are adapted to high moisture levels
• Wind intensity affects an ecosystem

  Plant seeds are more likely to germinate in locations with lower wind intensity, which may also attract animals that depend on the plant to live nearby
• Soil mineral content affects an ecosystem

  Most plants require a high level of soil minerals to grow well
• Plants adapted to low soil mineral content

  • Carnivorous plants catch insects to compensate for the low level of soil mineral content
• Carbon dioxide concentration affects an ecosystem

  Higher carbon dioxide concentration leads to more plant growth
• Oxygen concentration affects an ecosystem

  Aquatic animals cannot survive in areas with low oxygen concentration
• Biotic factors that may affect an ecosystem

  • Food
  • New predators
  • New pathogens
  • Competition
• Adaptations


  Features that enable organisms to survive in their living environment
• Organisms living in extreme environments

  Extremophiles
• Examples of extreme living environments

  • High temperature
  • High pressure
  • High salt concentration
• Where extremophile bacteria can be found


  • In deep sea vents
• Population


  A species that occupy the same habitat
• Habitat


  The place in which an organism lives
• Community


  Populations of different species interacting
• Ecosystem


  The interactions between the biotic and abiotic factors in an area
• Food chains


  • Show the feeding relationships of different organisms and the flow of energy between the organisms
• Biomass


  The total mass of living material
• Trophic levels


  The stages in a food chain
• Arrows in a food chain

  Represent the direction of biomass transfer
• Simple food chain


  Producer → primary consumer → secondary consumer → tertiary consumer
• Producer


  An organism that makes its own food
• Primary producers


  • Photosynthetic organisms like green plants and algae that trap energy from the sun
• Primary consumer


  An organism that feeds on producers
• Secondary consumer


  An organism that feeds on primary consumers
• Tertiary consumer


  An organism that feeds on secondary consumers
• Predator


  A consumer that kills and eats other animals
• Prey


  An animal that is killed and eaten by another animal