interdependence and adaptation

• plants compete for: light, space + water and nutrients from soil
• animals compete for: mates, food and territory
• organisms have adaptations which enable them to survive in the conditions in which they already live
• extremophiles: organisms which live in extreme environments, may be tolerant to high levels of salt, high temperatures or high pressures

Animals may survive in the arctic due to

• thickness of insulating coat
• amount of body fat
• camoflague
• changes to surface area

Animals may survive in dry conditions due to

• changes to surface area
• extensive root systems - absorb water quickly over large area
• deep roots - access underground water
• water storage tissues

• changes in the environment affects the distribution of living organisms
• animals and plants are subjected to environmental changes
• such changes may be caused by living (change in competitor) or non-living factors (change in rainfall or temperature)
• living organisms can be used as indicators of pollution:
  - lichen can be used as air pollution indicators, particularly the concentration of sulfur dioxide in the atmosphere
  - invertebrate animals can be used as water pollution indicators of the concentration of dissolved oxygen in water
• environmental changes can be measured using non-living indicators such as oxygen levels, temperature and rainfall