microscopes

• What should you be able to do by the end of the video on using an optical microscope?

  Describe how to use an optical microscope to look at cells on a prepared microscope slide
• Why is it important to learn the details of using an optical microscope?

  It could come up in the exam as a six mark essay question
• What is the main part of the optical microscope where the slide is placed?

  The stage
• What is the function of the clips on the stage of the microscope?

  To hold the slide in place
• What is located below the stage of the optical microscope?

  A lamp or a mirror
• How does the mirror in some optical microscopes function?

  It reflects light up through the microscope slide
• What are the lenses above the stage called?

  Objective lenses
• How many objective lenses do most microscopes have?

  Three different objective lenses
• What are the typical magnifications of the objective lenses?

  Four times, ten times, or forty times
• What are the two focusing dials on the microscope?

  The coarse focusing dial and the fine focusing dial
• What is the magnification of the eyepiece lens?

  Ten times
• What is the first step in using an optical microscope to view a prepared slide?

  Place the slide onto the stage and use the clips to hold it in place
• Which objective lens should be selected first when viewing a slide?

  The lowest power objective lens, usually four times
• How do you position the objective lens when starting to view a slide?

  Position it so it almost touches the microscope slide
• Why is it important to look at the microscope from the side while adjusting the objective lens?

  To avoid damaging the slide
• What should you do after positioning the objective lens close to the slide?

  Look down through the eyepiece and slowly turn the coarse focusing dial
• What is the purpose of the fine focusing dial?

  To bring the cells into a clear focus
• How do you calculate the total magnification of the microscope?

  Multiply the magnification of the eyepiece lens by the magnification of the objective lens
• What is the total magnification when using a ten times eyepiece lens and a four times objective lens?

  $40 \text{ times}$
• What should you do after achieving focus with the lowest power objective lens?

  Select a higher power objective lens and adjust the fine focusing dial
• What can be seen when observing animal cells under an optical microscope?

  The nucleons, cytoplasm, and cell membrane
• What additional structures can be seen in plant cells under an optical microscope?

  The cell wall, cytoplasm, nucleus, vacuole, and chloroplasts
• How should you include a magnification scale in your drawing of cells?

  Place a clear plastic ruler over the stage and measure the diameter of the field of view
• What should you write on your drawing besides the magnification scale?

  The magnification, for example, 100 times
• Where can you find questions related to the required practical on using an optical microscope?

  In the vision workbook
• Why is it important to learn the details of using an optical microscope?

  It is crucial for performing the required practical and succeeding in exams.
• What are the limitations of detail visible under an optical microscope?

  You can only see limited detail such as the nucleons, cytoplasm, and cell membrane.
• What should you do if you want to make a labeled drawing of cells?

  Use a pencil to make a clear labeled drawing of the cells observed.
• What is the significance of including a scale bar in your drawing?

  It provides a reference for the size of the cells observed.
• What types of cells can be observed under an optical microscope?

  Animal cells and plant cells.