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• Magnification = Image Size/Actual Size
• What is resolution?

  The smallest distance between 2 points that can be seen as 2 points and not blurred into 1 point.
• What is magnification?

  how big something appears compared to its actual size
• What is a TEM?

  A Transmission Electron Microscope
• What is a TEM used for?

  examine thin slices of cells or tissues
• What is the total magnification of a TEM?

  x1 000 000
• What is a field of view?

  A circle of light that can be seen through the microscope.
• How can the size of a field of view be measured?

  A transparent ruler in mm
• What is the limit of resolution of a TEM?

  less than 1nm
• What has a TEM been used to see?

  cell structures that cant be seen with a light microscope
• What is a SEM?

  Scanning Electron Microscope
• What is an SEM used for?

  Examine surface structures of specimen
• What is the limit of resolution for SEM?

  less them TEM - less than 50nm
• the higher the resolution, the more detailed the image
• What sub-cellular structures are likely to be observed using a light microscope?

  Nucleus, cell wall, cell membrane, chloroplasts, mitochondria – larger organelle
• Why are some sub-cellular structures not visible using a light microscope?

  the maximum magnification is only x1500, it has a limited resolution and the organelle are too small
• What precautions are needed when preparing a microscope slide?

  Place it gently to not break the glass.

  Do not touch the glass part of the lenses with your fingers. 

  Always keep your microscope covered when not in use
• Why should samples of animal cells be disposed of in disinfectant?

  To prevent risk of contamination
• Why does the layer of specimen cells need to be thin?

  To allow light to pass through
• Why do we stain the specimen cells?

  Cells are transparent and colourless so the organelle need to become visible
• Why does the coverslip have to be carefully applied?

  To prevent air bubbles
• What is the highest magnification for the light microscope?

  X1500
• How is the focusing wheel used?

  Look through the eyepiece and turn the wheel until the cells are in focus
• When should the fine focusing wheel be used?

  To focus at higher magnification
• How is the actual size of a cell structure determined from microscope

  measurements?

  know the size of field in mm - convert to micrometres. count cells across field of view. divide size of field in um by number of cells
• How can more detail be observed in cells?

  Use an electron microscope as it has a better resolution
• Why is a coverslip placed on top?

  To keep it still and flat
• What is the order of the SI units?

  Milli (mm)

  Micro (um)

  Nano (nm)

  Pico (pm)
• How do you convert between the SI units?

  Milli to micro = mm to um = x1000

  Micro to nano = um to nm = x1000

  Nano to pico = nm to pm = x1000

  Pico to nano = pm to nm = /1000

  Nano to micro = nm to um = /1000

  Micro to milli = um to mm = /1000
• How do you calculate magnification of an image using its scale bar?

  Use a ruler to measure the length of the scale bar in mm

  Convert this measurement into the same units as the scale bar

  Divide the image scale bar length by the actual object scale bar length
• What is the function of a white blood cell?

  It is part of the immune system and it produces antibodies and antitoxins