Adaptations, interdependence and competition

• An ecosystem

  • Is all the organisms living in a habitat and non-living parts of the habitat.
• Competition

  • To survive and reproduce, organisms require resources from their habitat.
  • Trying to get enough of these resources results in competition.
• Community

  • Within a community, each species depend on other species for food, shelter, pollination.
  • If one species is removed it can affect the whole community.
  • This is called interdependence.
• A stable community

  • When all species and environmental factors are in balance so that the population stays fairly constant.
• Population

  • group of individuals of the same species
• Community


  Made up of many populations living together.
• What do plants compete for?

  • Light and space
  • Water and mineral ions from soil
• What do animals compete for?

  • Food
  • Mates
  • Territory
• Abiotic factors

  • Light intensity
  • Temperature
  • Moisture levels
  • Wind intensity
  • Soil PH and mineral contents
  • Carbon dioxide levels for plants
  • Oxygen levels for aquatic animals
• Biotic factors

  • New predators
  • Species outcompeting another
  • Availability of food
  • New pathogens/ diseases
• Adaptations

  • Organisms have adaptations which enable them to survive conditions in which they normally live
  • Structural, behavioural, functional adaptations
• Extremophiles

  • Organisms that live in a environments that are very extreme
  • Example ~ High temperature, pressure or salt concentrations.
  • Bacteria living in deep sea vents are called extremophiles.
• Estimating population size

  • Use a tape measure to lay out a survey area
  • Use a random number generator to create a set of coordinates to place the first quadrat.
  • Count the number of your chose plant species e.g dandelions
• Estimated population equation

  • = total area/area sampled x total n.o of dandelions counted
• Feeding relationships

  • Shows what organisms eat or are eaten by others.
  • Can be shown in food chains
  • Example ~ grass - rabbits - foxes
• Base of every food chain

  • Is a producer
  • These are plants or algae which photosynthesise.
  • Make glucose which feeds the rest of the food chain.
• Consumer

  • Above the producer.
  • Primary consumer then secondary consumer.
  • Animals that hunt are predators.
  • Those that are hunted are called prey.
• Decomposers

  • Are bacteria and fungi which break down dead organisms in a process called decomposition.
• Carbon cycle

  • How carbon is recycled in nature
  • It relies on decomposers to return carbon to the atmosphere as carbon dioxide through respiration.
• Carbon cycle

  1. Carbon enters the atmosphere from respiration & combustion.
  2. Carbon dioxide is absorbed by producers to photosynthesis.
  3. Animals feed on plants, passing the carbon compounds along the food chain. They also exhale C02 through respiration but eventually die.
  4. Dead organisms are eaten by decomposers and carbon in their bodies returns to the atmosphere as carbon dioxide.
• The water cycle

  • Provides fresh water for plants and animals on land before draining into seas.
  • Water is continuously evaporated and precipitated.