Microscopy Practical

• What is the primary tool used in many biological experiments?

  A microscope
• Why is it important to know how to use a microscope?

  It is a key tool in many biological experiments
• What are the main parts of a microscope and their functions?

  • Light source: illuminates the specimen
  • Stage: holds the specimen slide
  • Objective lenses: magnify the specimen
  • Eyepiece lens: further magnifies the image
  • Coarse and fine focus dials: adjust focus
• What is the first step in setting up a microscope?

  Adjust the mirror to ensure adequate light
• What should you do to ensure good visibility of the specimen under the microscope?

  Ensure the light source is adjusted to create a bright circle
• What is the lowest magnification lens on a microscope typically used?

  The times 4 lens
• How do you carry a microscope safely?

  Use the handle and support the base with another hand
• What are the objective lenses on a microscope typically labeled as?

  Times 4, times 10, and times 40
• What is the total magnification when using the times 4 objective lens and the eyepiece lens?

  40 times magnification
• What is the purpose of adding iodine to the onion skin sample?

  To stain the starch in the cells for better visualization
• How should you handle a glass cover slip when preparing a microscope slide?

  Hold it by the edges to avoid fingerprints
• What should you do if there is excess iodine on the slide?

  Use a paper towel to dab away the excess
• Why is it important to have the cover slip on the upper surface of the slide?

  It ensures proper focusing of the microscope
• What should you do if you cannot focus on your specimen?

  Ensure you are using the lowest magnification lens
• What is the purpose of the coarse focus dials on a microscope?

  To make large adjustments to the focus
• What is the function of the fine focus dials?

  To make small adjustments for precise focusing
• How do you increase the magnification after focusing on a specimen?

  Spin the next objective lens into position
• What should you do when switching to a higher magnification lens?

  Ensure the lens does not touch the slide
• Why is it important to avoid making large adjustments when focusing?

  It can damage the specimen or the lens
• What are the steps to measure the size of cells under a microscope?

  1. Use the middle magnification lens (times 10).
  2. Focus on the specimen.
  3. Move the slide to view a row of whole cells.
  4. Measure the field of view with a ruler.
  5. Convert measurements to micrometers (1 mm = 1000 micrometers).
  6. Divide the total width by the number of cells to find average cell size.
• What is the average size of the onion cells if the field of view is 2000 micrometers wide and contains four cells?

  500 micrometers
• What is the significance of recording cell size in a practical experiment?

  It helps in understanding the characteristics of the specimen
• What is the final step after preparing the microscope slide?

  Place it on the stage under the clips