Cells and Respiration

• Organisms are made up of cells. Most organisms are multicellular and have cells that are specialised to do a particular job.
• Microscopes are needed to study cells in detail.
• Light microscope


  Cells range in size: animal cells are between 0.01 mm – 0.05 mm, plant cells are between 0.01 mm – 0.10 mm
• The human eye can see objects as small as around 0.05 mm. A microscope is required to see cells in any detail.
• Microscope


  Magnifies the image of a biological specimen so that it appears larger
• Compound microscope


  Uses two lenses, the objective lens and the eyepiece, to magnify the specimen
• Calculating the magnification of the microscope

  Magnification of the microscope = magnification of eyepiece × magnification of objective
• Magnification


  • ×10
  • ×4
  • ×40