Organisation of an ecosystem

• Random Sampling


  1. Place tape measure (x2)

  2. Randomly generate quadrat Co-ordinates

  3. Count + record clover numbers in quadrat

  4. Repeat 10 times

  5. Find mean

  6. Calculate estimated population size
• Systematic Sampling


  1. Place tape measure

  2. Place Quadrat at regular spaced intervals (2m)

  3. Count clovers and record

  4. Repeat ten times

  5. Calculate population size: total area x mean number of clovers / quadrat area
• Adaptations


  • Structural: A physical part or feature of an organism
  • Behavioural: The way an organism behaves
  • Functional: Biological processes within the organism
• Structural adaptations


  • White fur on polar bear provides camouflage in snow; not detected by predators
• Behavioural adaptations


  • Rabbits dig burrows in which to live and raise offspring
• Functional adaptations


  • Snakes produce venom to kill prey
• Adaptations to cold regions

  • Small surface area: volume ratio to minimise heat loss
  • Thick layer of fat (e.g. seal blubber, polar bear) insulates against cold
• Levels of organisation in an ecosystem

  • Feeding relationships
  • Food chains
  • Producers
  • Consumers
  • Predators
• Producers


  • They begin food chains
  • They are always photosynthetic organisms e.g. green plants
  • Through photosynthesis they make glucose
  • Glucose is transferred to other biological molecules that make up the biomass
• Feeding relationships in an ecosystem

  1. Producers are eaten by primary consumers

  2. Primary consumers are eaten by secondary consumers

  3. Secondary consumers are eaten by tertiary consumers
• Prey


  The organism that is eaten
• Predator


  The organism that eats the prey
• Studying an ecosystem


  1. Use transects and quadrats

  2. Calculate mean, mode and median

  3. Draw graphs to show population cycles between predators and prey
• Population of prey increases


  Population of predators increases
• Population of predators increases


  Number of prey decreases after some time
• When there isn't enough prey to feed all predators

  The population of predators will decrease, allowing the prey to increase again
• Materials cycled through an ecosystem

  • Carbon
  • Water
• The carbon cycle


  1. CO₂ is removed from the air in photosynthesis by green plants and algae

  2. Carbon moves up the food chain as plants are eaten by animals

  3. CO₂ is returned to the air when plants, algae and animals respire or decompose

  4. CO₂ is returned to the air when wood and fossil fuels are burned
• Required practical


  Measuring population size in a habitat
• Random Sampling method

  1. Choose a starting point on the school field in an area where the grass is cut

  2. Use random numbers to generate a set of coordinates

  3. Place your first quadrat

  4. Count the number of different plant species within the quadrat

  5. Return to your starting position and repeat steps two to four times using different coordinates

  6. Use the following equation to estimate the number of daisies in the field: Estimated population = area sampled x number of daisies in sample / total area
• Systematic Sampling method


  1. Stretch a 30m tape from the base of a tree out into an open area of the field. This will be the transect

  2. Place a quadrat at 0m and count the number of daisies within the quadrat

  3. Repeat step 2 six times moving the quadrat 5m further each time

  4. At each location you may measure light intensity, soil hydration/pH to determine if this factor affects the abundance of daisies