Relationships Between Organisms

• What is an ecosystem?

  All the organisms living in a habitat AND the non-living parts of the habitat
• What are the different levels of organisation in an ecosystem?

  Individual organisms , populations (groups of individuals of the same species) and communities (many populations living together
• Communities are made up of many populations living together
• Organisms require certain resources from their habitat and other living organisms to survive and reproduce - Trying to get enough resources results in competition
• How do plants in a community or habitat compete with each other?

  They compete for light , water space and mineral ions from soil
• How do animals compete with each other?

  They compete for food , mates and territory
• What is interdepence?

  When species rely on each other for things like food , shelter , pollination or seed dispersal
• Interdependence means that removing one species from a habitat affects the whole community
• In a stable community , all the species and environmental factors are in balance so that population sizes stay fairly constant
• What are some examples of stable communities?

  Tropical rainforests and ancient oak
• What do all ecosystems need to be self supporting?

  They need energy - which is usually transferred into the ecosystem as light energy for photosynthesis in green plants - green plants are the start of the food chain