ecology

• what is a habitat?

  the place where organisms live
• what is a population?

  all the organisms of one species living in a habitat
• what is a community

  the populations of different species living in a habitat
• abiotic features

  non-living factors of the environment
• biotic features

  living factors of the environment
• ecosystem

  the interaction of a community of living organisms (biotic) and with the non-living (abiotic) parts of their environment
• Organisms must compete for resources to survive
• Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil. Animals often compete with each other for food, mates and territory.
• Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community. This is called interdependence
• A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
• Abiotic (non-living) factors which can affect a community are:

  • light intensity
  • temperature
  • moisture levels
  • soil pH and mineral content
  • wind intensity and direction
  • carbon dioxide levels for plants
  • oxygen levels for aquatic animals
• Biotic (living) factors which can affect a community are:

  • availability of food
  • new predators arriving
  • new pathogens
  • one species outcompeting another so the numbers are no longer sufficient to breed.
• Organisms have features (adaptations) that enable them to survive in the conditions in which they normally live. These adaptations may be structural, behavioural or functional.
• structural adaptations : features of an organisms body structure
• behavioural adaptations : ways organisms behave, many species migrate to warmer climates during the winter to avoid the problems of living in cold conditions
• functional adaptations : these are things that go on inside an organisms body that can be related to the processes like reproduction and metabolism
• what are extremophiles ?

  organisms that live in environments that are very extreme, such as at high temperature, pressure, or salt concentration.
•  All food chains begin with a producer which synthesises molecules. 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.
• environmental changes can cause the distribution of organisms to change, a change in distribution means a change in where the organism lives, environmental changes that can effect organisms in this way include :

  • Availability of water
  • change in temperature
  • Change in the composition of atmospheric gases
• environmental changes can be caused by seasonal factors, geographic factors or human interaction
• All materials in the living world are recycled to provide the building blocks for future organisms
• 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.
• what effects the rate of decay ?

  • Temperature
  • Oxygen availability
  • Water availability
  • Number of organisms
• how does temperature effect rate of decay ?

  warmer temps make things decompose quicker as they increase the rate that the enzymes involved in decomposition work at, if it is too hot then the decomposition slows down or stops as the enzymes denature or they are destroyed

  really cold temps also slow the rate of decay
• how does oxygen effect rate of decay ?

  many organisms require oxygen to respire which they need to do to survive, the Mirco-organisms invloved in anaerobic decay do not need to though
• how does water effect rate of decay ?

  Decay takes place faster in moist environments as the organisms involved in decay need water to Cary out biological processes
• how does the number of decay organisms effect rate of decay ?

  The more there are the faster decomposition happens
• Gardeners and farmers try to provide optimum conditions for rapid decay of waste biological material. The compost produced is used as a natural fertiliser for growing garden plants or crops.
• Anaerobic decay produces methane gas. Biogas generators can be used to produce methane gas as a fuel.
• Environmental changes affect the distribution of species in an ecosystem. These changes include:

  • temperature
  • availability of water
  • composition of atmospheric gases.

  The changes may be seasonal, geographic or caused by human interaction.
• 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. Many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction.
• 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