cpac 7

• Dissections are essential to a complete understanding of internal biological functions
• There are some ethical issues with dissection, including the way in which the animals are raised and killed
• Equipment


  • Live locust
  • Dead locust
  • Forceps
  • Scissors
  • Cork board
  • Dissecting pins
  • Seeker
  • Specimen jar or syringe
  • Microscope slides and coverslips
  • Methylene blue stain
  • Dissecting microscope
  • Hand lens
  • Pipette
  • Watch glass
• Risk Assessment


  • Hazard
  • Risk
  • Safety Precaution
  • In emergency
  • Risk Level
• You should wear a lab coat, gloves and eye protection for all dissections
• Dissection Tips


  • Pin the locust to the dissecting board and remove the exoskeleton
  • Locusts have spiracles controlled by sphincters, tracheae held open by chitin spirals, and tracheoles where gas exchange occurs. They may also have air sacs
  • Flood the specimen with water so that the tracheae show up as silvery-grey
  • Watch for rhythmic movements of the abdomen - this is the locust mechanically ventilating its gas exchange system
• Tips for Biological Drawings

  • Use an HB pencil and a white, unlined sheet of paper
  • Draw in the centre of the page, and have the drawing take up at least half of the paper
  • Label the diagram, also in pencil
  • Use a ruler for straight lines and for labelling
  • Use clear lines - don't smudge or feather them
  • Only draw what you can see
  • Do an outline first
  • Do not use shading or colour
  • Write the lens power that has been used somewhere on the diagram