ecology

• what is an ecosystem?

  all the organisms that live in a habitat and the non-living parts of the habitat
• what are the different levels of organisation in an ecosystem?

  levels:

  • individual organisms
  • populations (groups of individuals of the same species)
  • communities (made up of many populations living together)
• to survive and reproduce, organisms require certain resources from their habitat and the other living organisms there
• what is competition?


  the interaction between organisms striving for the same resources
• what is interdependence?


  when one organism relies on another for certain resources
• because of interdependence, removing one species from a habitat can affect the whole community
• what factors can communities be affected by?

  biotic and abiotic factors
• what are abiotic factors?

  light intensity, temperature and moisture levels
• what are biotic factors?

  availability of food, new predators, new pathogens
• what are adaptations?


  the gradual change in a particular organism, over many generations, to become better suited to its environment
• adaptations can be..


  structural, behavioural or functional
• what is an extremophile?


  Organism that thrives in extreme environments.
• what are some extreme conditions?

  high temp, high pressure or high salt concentrations
• what is a population?

  A group of individuals of the same species living in the same habitat
• what is a quadrat?

  a square frame (usually between 0.25m^2 and 1m^2) used for sampling organisms in their natural environment
• what is a transect line?


  a fixed line along which populations are sampled
• investigating population size RP

  investigating the population size of a common species in a habitat
• whats the method for investigating population size RP?

  method:

  1. place a quadrat on the ground at random
  2. count the number of individual plants of one species in the quadrat
  3. repeat this process a number of times and work out the mean number of plants
  4. work out the mean number of plants in 1m^2
  5. measure the area of the whole habitat and multiply the number of plants in 1m^2 by the whole area
• what is the dependent variable of population RP?

  number of plants in the quadrat
• carbon cycle

  
• all materials in the living world need to be recycled so that they can be used again in future organisms
• what is the carbon cycle?

  the constant recyling of carbon through the process of life, death and decay
• what does the carbon cycle rely on?

  decomposers to return to the atmosphere as carbon dioxide
• how does carbon dioxide return to the atmosphere?

  through respiration
• what is the water cycle?


  a series of processes that circulate water through the environment (fresh water circulates between living organisms, rivers and the sea)
• what do all food chains begin with?

  a producer
• what is a producer?

  an organism that can make its own food e.g. plants
• what is usually the producer?

  green plants which make glucose molecules by photosynthesis
• what are producers eaten by?

  primary consumers
• what eats the primary consumer?

  secondary consumer
• what eats the secondary consumer?

  Tertiary consumer
• what are consumers?


  predators
• what are predators?


  Animals that hunt and kill other animals for food.
• what is prey?


  an organism that is hunted and killed by a predator for food
• what are top consumers?

  apex predators
• what are apex predators?

  top consumers in the food chain; has no predators
• in a stable community the numbers of predators and prey rise and fall in cycles
• what is biodiversity?


  the variety of living organisms and the ecosystems in which they live
• why does high biodiversity help ecosystems to be stable?

  because species depend on each other for food and shelter
• the future of humans relies on maintaining a good level of biodiversity