LS 7 and 8 Notes


  • Animals need food, water, shelter, space and gases.They may need to compete for these resources.Having to much can be as harmful as too little.
  • Organisms in a population not only compete with each other for resources, but also compete for mates and/or a territory
  • Having a territory allows members of a population to have an adequate habitat to meet their basic needs.(Territorial Imperative)
  • There needs to be a social order in a population so that resources and work are equally shared. (Social hierarchy)
  • The behavior of one or the behavior of many may influence an entire population
  • Populations that rely on each other form communities
  • Community resources are shared among producers, consumers and decomposers
  • Producers (autotrophs)are organisms who generally go through photosynthesis-make their own food internally
  • Consumers (heterotrophs) are organisms that eat other organisms-can’t make their own food internally
  • Decomposers are organisms (bacteria and fungus) that break down dead or decaying material
  • Scavengers eat dead organisms (they don’t break them down like bacteria)
  • Predator/Prey relationship or predation is where one consumer hunts and eats another organism
  • Members of one population may compete with members of the same population or may compete with organisms of another population for limited resources
  • Symbiotic relationships can occur when organisms work and live together.There are three types of symbiotic relationships.
    1. In commensalism one benefits and the other is neither helped or harmed (win/no affect) Ex: sharks and remoras
    2. mutualism both organisms benefit ( win/win) Example: saguaro cactus and long nosed bat
    3. parasitism one organism benefits and the other is harmed (win/lose) Example: tick and human