Biology Paper 2,Nov/Dec 2012  
Questions:   1 2 3 4 5 6 7 8   Main
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Question 3 

Question 3

  1. (i)   What is pollution?                                                                                      [ 2 marks ]

(ii)   Name three water pollutants                                                                    [ 3 marks ]
(iii)  State five harmful effects of sulphur dioxide in the atmosphere              [5 marks  ]

  1.  (i)   Explain the term population                                                                     [3 marks  ]

(ii)   Explain how a pitfall trap is used to measure the population size of
       organisms in a habitat.                                                                            [ 7 marks ]


 This was also a popular question among the candidates.  Majority of the candidates could define  pollution and name water pollutants correctly with perfect spellings.
Many candidates could define population correctly but could not describe the use of pitfall trap and were instead treating it as a quadrat  
Expected answers include:                                             

(b)    Use of a pitfall trap in sampling organisms

         It consists of

    • a large jar with straight sides buried in a hole in the soil; with the mouth upwards;
    • food as bait is put into the trap/large jar;
    • the traps are  placed randomly within the habitat;
    • and examined regularly/at intervals;
    • organisms lured by the bait; fall into the trap;
    • the organisms captured are collected;
    • identified;
    • counted;
    • released.


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