topic 9

• devise a practical to find the distribution of plants

  • place multiple tape measures along the length of the feild
  • generate 10 random co ordinates
  • place the quadrat on each co ordinate and count the amount of dandelions
  • calculate the mean number of dandelions per quadrat
  • estimate total population size
• what do fertilisers do?

  replace the lost nutrients so the fertilisers supply with nutrients
• eutriphication?

  . caused by the excess of nutrients that are leached into waterways

  mineral ions leach into lakes, causing algae to grow

  . the growth of algae prevents plants from reaching the light below

  the lack of light prevents photosynthesis , which causes plants to die

  decomposers use oxygen to respire so the oxygen levels in the water deplete
• how does the nitrogen cycle work?

   nitrogen is converted from nitrogen gas in the atmosphere into a form that can be used by plants

  
  

  ammonia is converted to nitrates by nitrifying bacteria in the soil.

  
  

  nitrogen from the air is converted into soluble ions that plant roots can absorb.

  
  

  Decomposers break down the bodies of dead organisms, urine and faeces resulting in nitrogen being returned to the soil as ammonia. This ammonia is converted to nitrates by nitrifying bacteria.

  
  

  1n some conditions denitrifying bacteria in the soil break down nitrates and return nitrogen back to the air