Yr 9 science topics

• What is the primary function of microscopes?

  To magnify images of specimens
• What important discoveries have light microscopes allowed us to make?

  Discoveries about the structures inside cells, such as the nucleus
• What are the limitations of light microscopes regarding magnification?

  They have a limited magnification that cannot easily view structures inside the nucleus
• What does limited resolution in light microscopes mean?

  It means the image is blurred, preventing fine detail from being seen
• Why was the electron microscope invented?

  To explore structures inside cells in detail
• What are the key advantages of electron microscopes over light microscopes?

  They have much greater magnification and resolution
• What can be seen in the nucleus when using an electron microscope?

  Detail in the nucleus that cannot be seen with a light microscope
• What is the formula for calculating magnification?

  Magnification = size of the image / size of the real object
• How do you calculate the size of the real object if you know the image size and magnification?

  The size of the real object is the size of the image divided by the magnification
• What are the advantages of using an electron microscope?

  • Greater magnification
  • Higher resolution
  • Ability to see fine details in specimens
• What steps should you follow to calculate magnification?

  1. Measure the size of the image.
  2. Measure the size of the real object.
  3. Use the formula: Magnification = size of the image / size of the real object.
• What is the significance of the magnification formula?

  • It allows for the calculation of how much larger an image appears compared to the actual object.
  • Essential for understanding the capabilities of different microscopes.
• 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 microscope slide in place
• What is located below the stage of an optical microscope?

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

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

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

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

  Four times, ten times, or forty times
• What is the magnification of the eyepiece lens?

  Ten times
• What are the two focusing dials on the microscope?

  The coarse focusing dial and the fine focusing dial
• 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?

  Forty times
• What should you do after achieving focus with the low-power objective lens?

  Select a higher power objective lens and adjust the fine focusing dial
• What might you see when looking at animal cells under an optical microscope?

  Nucleus, cytoplasm, and cell membrane
• What details can be seen in plant cells using an optical microscope?

  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 be included in your drawing besides the cells?

  A magnification scale and the magnification value
• What are the key parts of an optical microscope and their functions?

  • Stage: Holds the microscope slide
  • Clips: Secure the slide in place
  • Lamp/Mirror: Provides light to view the slide
  • Objective Lenses: Magnify the image (4x, 10x, 40x)
  • Eyepiece: Contains the eyepiece lens with 10x magnification
  • Coarse and Fine Focusing Dials: Adjust focus
• What is the procedure for using an optical microscope to view a prepared slide?

  1. Place the slide on the stage and secure with clips.
  2. Select the lowest power objective lens (4x).
  3. Position the objective lens close to the slide.
  4. Look through the eyepiece and adjust the coarse focusing dial.
  5. Use the fine focusing dial for clear focus.
  6. Calculate total magnification and adjust lenses as needed.
• What are the limitations of viewing cells with an optical microscope?

  • Limited detail visible (e.g., cannot see ribosomes)
  • Dependent on the type of cell being viewed
  • Cannot view living cells in detail
• What is the function of the nucleus in animal cells?

  To enclose the genetic material (DNA)
• What is the cytoplasm and its role in the cell?

  A watery solution where chemical reactions take place
• What is the function of the cell membrane?

  To control the molecules that can enter and leave the cell