Ecology

• populations are all the organisms of one species living in a habitat
• communities are the populations of different species living in a habitat
• abiotic factors are non living factors of the enviroment
• biotic factors are the living factors of the enviroment
• ecosystem is the interaction of a community of living organisms with non living parts of the environment
• interdependence is any major change in the ecosystem that can have lots of effects
• competition:

  • plants = compete for light, space, water and mineral ions
  • animals = compete for space, food, water and mates
• adaptations allow organisms to survive
• adaptations can be either:

  • structural
  • behavioural
  • functional
• structural adaptations are features of an organisms body structure
• behavioural adaptations are ways than an organsims behaves
• functional adaptations are processes that go on inside the body
• a stable community is where all the species and enviromental factors are in balance so the population size stays constant
• abiotic factors:

  • light intensity
  • temperature
  • moisture levels
  • soil pH
  • wind intensity
  • CO2 concentration
  • oxygen levels
• biotic factors:

  • availability of food
  • new predators
  • new pathogens
  • competition
• extremophiles are microorganisms that arre adapted to live in very extreme conditions
• Organisms that are able to photosynthesise produce biomass for the Earth
• Feeding relationships within a community can be represented by food chains
• All food chains begin with a producer which can photosynthesise. This is usually a green plant or alga which makes glucose by photosynthesis.
• Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers
• Consumers that kill and eat other animals are predators, and those eaten are prey
• In a stable community the numbers of predators and prey rise and fall in cycles
• All materials in the living world are recycled
• The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.
• The water cycle provides fresh water for plants and animals on land before draining into the seas. Water is continuously evaporated and precipitated.
• Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem.
• A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment
• The future of the human species on Earth relies on us maintaining a good level of biodiversity.
• Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced.
• Unless waste and chemical materials are properly handled, more pollution will be caused.
• Pollution can occur:

  • in water, from sewage, fertiliser or toxic chemicals
  • in air, from smoke and acidic gases
  • on land, from landfill and from toxic chemicals.
• Pollution kills plants and animals which can reduce biodiversity.
• Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.
• The decay or burning of the peat releases carbon dioxide into the atmosphere
• Peat formation is the result of incomplete decomposition of the remains of plants growing in waterlogged conditions
• Peat is a deposit of partially decayed plant matter, which collects in bogs
• Large-scale deforestation in tropical areas:

  • provides land for cattle and rice fields
  • grows crops for biofuels
• The consequences of global warming:

  • Changes in or loss of habitats due to these extreme weather events
  • Decreases in biodiversity as food chains are disrupted and extinction rates increase
  • Increases in migration of species to new places
  • Increased spread of disease.
• Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming
• programmes have been put in place to reduce the negative effects of humans on ecosystems and biodiversity