2.Organisation

• What type of organisms, are 'producers'?

  • Photosynthetic organisms
• What are producers?


  • Start of a food chain
  • green plants and algae produces glucose by photosynthesis
• Levels of organisation 


  1. Producer
  2. Primary consumer
  3. Secondary consumer
  4. Tertiary consumer
• What are 'predators'?


  • Consumers that kill and eat other animals.
• What are 'prey'?


  • Animals that are eaten by predators
• Number of predators and prey in a stable community :

  • rise and fall / fluctuate in cycles
• How to decide where quadrats are placed?

  • Grid and coordinates
  • to achieve randomness to avoid bias
• Why are transects and quadrats used?

  • ecologists to determine the distribution and abundance of species in an ecosystem.
• How to calculate total population size

  total population size = total area (large) / area sampled x number of organisms of that species counted in the sample
• Plan an investigation to test this hypothesis : Quadrat


  • Placing quadrat
  • Large number of quadrats used
  • Place quadrat along transect quadrats placed at coordinates
  • Move quadrats up regular intervals along transect
  • in each of contrasting areas containing the flowers
  • for each quadrat count number of flowers
  • for each quadrat measure x
  • compare data with y
  • repeat and calculate a mean
• Explain how living things are involved in the carbon cycle (6)


  • green plants photosynthesise
  • photosynthesis takes in carbon dioxide
  • green plants use carbon to make protein / carbohydrate
  • animals eat green plants
  • green plants respire
  • animals respire
  • respiration releases carbon dioxide
• What are the role of microorganisms in the carbon cycle?

  • Microorganisms break down dead organisms
  • Microorganisms respire
  • Respiration releases carbon dioxide
  • Returning to the atmosphere
• How do microorganisms return mineral ions to the soil?

  • break down dead organisms into mineral ions
  • returned to the soil
• Key words describing the water cycle

  • evaporation into water vapour from earth's source from heat of sun
  • condensation as water rises it cools and condenses
  • precipitation rain from clouds fall
  • drainage into seas / oceans
  • transpiration of water evaporating from leaves
• Water is....?


  • continuously and evaporated
• Why take a large number of results?

  • More representative of the sample and to calculate a reliable mean
• What is decomposition?


  • Breaking down dead organic matter by organisms called decomposers into simpler organic matter e.g carbon dioxide, mineral ions, water, simple sugars
• Example of decomposers


  • Bacteria
  • Fungi
• Why is decomposition important to living organisms?

  • ensures that materials such as carbon and mineral ions are recycled and returned to the environment
• 3 factors affecting the rate of decay by decomposition

  1. Temperature
  2. Water
  3. Oxygen
• How does temperature affect rate of decay?

  • Enzymes are involved in decomposition reaction.
  • high temperature, increases the rate of enzyme activity (optimum), so increasing the rate of decay
  • temperature too high, enzymes involved denature, so loses function, decay stops, decomposer dies.
  • If temperatures too low, rate of enzyme activity is very slow so rate of decay is slow
• How does oxygen affect rate of decay?

  • Oxygen required for aerobic respiration
  • to release energy for decomposition
  • rate of decay decreases as oxygen availability decreases
• How does water affect rate of decay?

  • decomposers require water to survive as water is essential for certain biological processes.
  • many decomposers function by secreting enzymes onto decaying biological matter and absorb products of chemical digestion
  • without water, reaction cannot occur
  • as water availability decreases, rate of decay decreases
• What do gardeners and farmers do to stimulate rapid decay?

  • Provide optimum conditions for rapid decay of waste biological material
• What does decay produce?

  C...

  • Compost
• How is compost used by gardeners and farmers?

  • Rich in nutrients
  • Natural fertiliser for growing garden plants and crops
• What type of respiration do some decomposers break down dead organic matter?

  • Anaerobic decay without oxygen
• What does anaerobic decay produce?

  • Methane gas
• What do biogas generators do?

  • Produce methane gas as a fuel
• Investigating the rate of decay

  • investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change
• RP 10 : Independent variable 


  • Changing the temperature
• RP 10 : Dependent variable 


  • time taken for milk solution to turn colourless
• RP 10 : Control variables

  • Volume / concentration of lipase solution
  • Volume / concentration of milk
  • Volume / concentration of sodium carbonate solution
• Why will the pH of the milk decrease as milk is added?

  • lipase breaks down fats in the milk into fatty acids
• Why must you do whilst adding lipase solution to milk + sodium carbonate solution?

  • Stir
• Equipment needed to investigate rate of decay

  • Water bath
  • Small beaker : milk, lipase, sodium carbonate solution
  • pipette
  • stopwatch
  • stirring thermometer
  • test tubes
• What is the indicator used?

  • Phenolphthalein
• What colour is phenolphthalein in acids and alkalis?

  • Pink in alkalis
  • Colourless in acids
• Part 1 - Describe the milk practical : Setting up the solutions

  1. place 5cm^3 lipase solution into test tube and label 'lipase'
  2. place 5 drops of phenolphthalein solution with dropping pipette and label with milk
  3. use dropping pipette to add 5cm^3 milk to tube with phenolphthalein
  4. use another pipette to add 7cm^3 sodium carbonate solution to phenolphthalein. This should be pink.
  5. place thermometer into milk solution
• Part 2 - Describe the milk practical

  1. put both test tube into the water bath. should have water boiled from a hot kettle. Wait until the contents reach the same temperature as the water bath.
  2. use another dropping pipette to add 1cm^3 lipase into milk, phenolphthalein and sodium carbonate test tube.
  3. Stir contents of test tube until colour change to colourless