Biology topic 7

• Ecology


  The study of organisms and the environment they live in
• Biodiversity


  The number of different plant and animal species found in an area
• Field sampling


  Measuring the distribution of organisms in an ecosystem
• Habitat


  The place where an organism lives
• Population


  The number of one type of organism in an area
• Environment


  The factors in a habitat that affect organisms
• Community


  The total number of organisms from all the populations in an area
• Random quadrat sampling


  Placing quadrats randomly to measure the distribution of organisms
• Ecosystem


  An area where a community of organisms live and are affected by a range of environmental factors
• Temperature


  Can be measured using a thermometer
• Belt transect sampling


  Using quadrats placed along a line to measure changes in the habitat from one side to the other
• Biotic factors


  Living features of the environment, for the ways in which the presence of one species interacts with another
• Belt transect sampling is used in habitats where quadrats would not identify the change from one side to the other
• In a rocky seashore habitat, a belt transect can be used to sample the change from the low tide area to the high tide area
• Biotic factors


  • Competition, where the organisms in a habitat each try to obtain enough of a resource they both need to reproduce and survive
• In a habitat with slow moving animals, quadrats can be used to sample both the animals and the plants
• There is usually not enough of the resource to allow both organisms to thrive so the reproduction and ultimately the survival of both organisms is affected
• Quadrats in a belt transect can be placed continuously or at intervals depending on the distance involved
• Herbivores (Primary) feed on plants
• Abiotic factors


  Non-living factors that could affect the distribution of plants and animals
• Carnivores (Secondary) feed on primary consumers
• Abiotic factors that can be investigated

  • Wind speed
  • Soil moisture
  • pH
  • Light
  • Temperature
• Ecosystems use energy that comes from the sun
• Measuring wind speed


  Using anemometers
• Energy flow


  1. Producers use energy from the sun to produce food

  2. Primary consumers feed on producers

  3. Secondary consumers feed on primary consumers

  4. Tertiary consumers feed on secondary consumers
• Measuring soil moisture


  Taking soil samples, weighing them, drying them, and reweighing to calculate percentage moisture
• Measuring pH


  Using soil test kits or probes
• Trophic levels


  The different feeding levels in an ecosystem
• Measuring light


  Using light meters
• Producers photosynthesize to produce their own food and provide food/energy for other organisms
• Reliability means someone can repeat an investigation and get similar results
• Measuring temperature


  Using thermometers
• Validity indicates whether you are actually able to draw conclusions from the information
• Food chains show the feeding relationships which transfer substances, including carbon and nitrogen, as well as energy between several organisms
• Pyramid of numbers


  Represents the number of organisms involved in a food chain or food web
• For a food web to be sustainable, there must be enough food for secondary consumers
• There will usually be more producers than primary consumers, and more primary consumers than secondary consumers
• Pyramid of biomass


  Takes into account the size of the organisms involved, more accurate than pyramid of numbers
• How to draw a pyramid of numbers


  Obtain data, organisms may have to be killed
• Pyramids of biomass always decrease in biomass from producers to consumers