Size of Cells

• What is the typical size range of most animal and plant cells?

  0.01 – 0.10 mm
• What is the smallest size that can be seen with the naked eye?

  About 0.05 mm
• Why do we need a microscope to see cells in detail?

  Because cells are too small to be seen in detail with the naked eye
• What is the best unit to measure most cells?

  Micrometre, symbol μm
• When is it best to use the nanometre as a unit of measurement?

  For sub-cellular structures like ribosomes or organisms like viruses
• What is the symbol for nanometre?

  nm
• What is the symbol for micrometre?

  μm
• What are the differences between micrometre and nanometre in cell measurement?

  • Micrometre (μm) is used for most cells.
  • Nanometre (nm) is used for sub-cellular structures and viruses.
• How do we understand the size difference between cells?

  Using orders of magnitude
• What are the prefixes used to show multiples of units of measurement?

  • Cent: Multiply unit by 0.01
  • Milli: Multiply unit by 0.001
  • Micro: Multiply unit by 0.000001
  • Nano: Multiply unit by 0.000000001
• Centi

  10^-2
• Milli

  10^-3
• Micro


  10^-6
• nano


  10^-9
• Name the unit and its calculation using standard form

  Centi

  10^-2

  
• name the unit and its calculation using standard form

  Milli

  10^-3

  
• Name the unit and its calculation using standard form

  Micro

  10^-6

  
• Name the unit and its calculation using standard form

  Nano

  10^-9