(a) For each of the sections in bold in the passages below
  • Name the type of behaviour described,
  • give a reason for your choice,
  • suggest one advantage to the organism of this behaviour.


(i) Flatworms are simple softbodied animals with a flattened and elongated body. When placed in a petri dish that has one side illuminated and one side covered with a dark cloth as shown in the diagram, the following observations can be made. Flatworms swim quickly in random directions in bright light, but stop swimming in darkness.



(ii) If blowfly larvae are placed in the same apparatus (without water this time), the following observation can be made. Blowfly larvae move away from the light.



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