Required practicals for biology

• Optical microscope


  Used to look at cells on a prepared microscope slide
• Optical microscope


  • Has a stage to place the microscope slide
  • Has a light source (lamp or mirror) to illuminate the slide
  • Has objective lenses with different magnifications (4x, 10x, 40x)
  • Has an eyepiece lens with 10x magnification
  • Has coarse and fine focusing dials
• Using an optical microscope to view a prepared slide


  1. Place slide on stage and secure with clips

  2. Select lowest power (4x) objective lens

  3. Slowly turn coarse focus dial to lower lens near slide

  4. Look through eyepiece and turn coarse focus dial to bring cells into focus

  5. Use fine focus dial to sharpen focus

  6. Calculate total magnification by multiplying eyepiece (10x) and objective (4x, 10x, 40x) lens magnifications
• What can be seen under an optical microscope


  • Animal cells: nucleus, cytoplasm, cell membrane, possible mitochondria
  • Plant cells: cell wall, cytoplasm, nucleus, possible vacuole and chloroplasts
• Optical microscopes have limited detail - cannot see organelles like ribosomes or lysosomes
• Drawing of cells should include a magnification scale, measured by placing a ruler on the stage