Distribution of organisms

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  • Created by: Sophie
  • Created on: 07-04-13 16:37

Distribution of organisms

  • habitat-where an organism lives
  • distribution of a an organism affected by environmental factos:
    • temperature
    • avalibility of water
    • avalability of oxygen & carbon dioxide
    • availability of nurtients
    • amount of light
  • two ways to study distribution of an organism:
    • measure how common an organism is in two sample areas
    • study how distribution changes across an area
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Quadrats

  • used to compare how common an organism is in two sample areas
  • steps:
    • choose first sample area 
    • divide area into grid
    • pick ramdom point
    • place 1m   quadrat on point
    • count organisms in quadrat
    • repeat steps in first area
    • work out mean
    • repeat all steps in second sample area
    • compare the two means

(http://www.nhbs.com/images/jackets_resizer_xlarge/17/175986.jpg)

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Population size

  • work out mean mumber of organisms per m 
  • then mulitiply mean by total area
  • example- open field is 800m squared, average of 22 daisies per m 

22     800= 17600

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Transect

  • transect-lines
  • how organsims are distributes across a line
  • steps:
    • mark out line using tape measure
    • count all the organsims touching the line
    • or
    • place quadrats along the line (next to each other or at intervals)

(http://t2.gstatic.com/images?q=tbn:ANd9GcR5tdiqot8uRFs44IHB2rwO9s8o220uq2N74CwtIjt0q3cC7UP9)

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Comments

Sophie

if you are going to use these cards everywhere is says m (metres) you need to add a sqaured on the end and there should be a times sign between 22 and 80 on the 3rd card, sorry guys :) ***

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