Required Practicals

• What should you use to draw your observations when using a light microscope?

  A pencil
• Why might you add stain to the sample on a microscope slide?

  To enhance contrast and visibility of the sample
• What is the formula for calculating magnification?

  magnification = image size / real size
• If a spinner is 50 µm wide, what is the width of the image under a magnification of x 100?

  5000 µm
• Why is it useful to write numbers in standard form when using microscopes?

  Because microscopes can see tiny objects, making large numbers more manageable
• How can you express 0.017 in standard form?

  1. 7 x 10^-2
• How do you determine the power of 10 when converting to standard form?

  By counting the number of places the decimal point moves
• If a mitochondrion is approximately 0.0025 mm long, what is its standard form representation?

  1. 5 x 10^-3
• What is the real width of a cheek cell if its image is 2.4 mm wide under ×40 magnification?

  60 µm
• What should you keep an eye on when using the magnification formula?

  The units must be the same
• What is the process for calculating the image size using magnification?

  1. State the formula: image size = magnification × real size
  2. Fill in the values for magnification and real size
  3. Calculate the image size
  4. Ensure the units are consistent
• What are the steps to convert a number to standard form?

  1. Identify the first non-zero digit
  2. Move the decimal point to the right or left
  3. Count the number of places moved
  4. Represent this count as a power of 10 (negative for left, positive for right)