RP01 - Microscopy

• What is the aim of the microscopy practical?

  Using a light microscope to investigate plant and animal cells.
• What is the first step of the microscopy practical?

  Preparing the Onion Sample.
• What equipment is needed to prepare the onion sample?

  Onion, scalpel, forceps, white tile, microscope slide, iodine solution.
• What do you do with the onion epidermis layer?

  Peel a thin layer using forceps and place it flat on a microscope slide.
• What do you add to the slide after placing the onion sample?

  A drop of water and 2 drops of iodine solution to stain the cells.
• Why is iodine solution used in the microscopy practical?

  To stain the cells and highlight structures like the nucleus.
• What is the second step of the microscopy practical?

  Adding the cover slip carefully.
• How do you place the cover slip correctly?

  Lower it at an angle, placing one edge first to avoid air bubbles.
• What should you do if there’s excess stain on the slide?

  Soak it up gently using a paper towel.
• What is the third step of the microscopy practical?

  Setting up the microscope.
• Where should the prepared slide be placed on the microscope?

  On the stage of the microscope.
• How do you light the slide on the microscope?

  Turn on the built-in light or use a mirror to reflect light through the condenser.
• What is the fourth step of the microscopy practical?

  Focusing the microscope.
• Which objective lens should you start with?

  The lowest power lens (smallest magnification).
• What do you do before looking through the eyepiece?

  Use the coarse focus knob to raise the stage until the cover slip is just below the lens.
• How do you bring the specimen into focus?

  Look through the eyepiece and slowly lower the stage using the coarse focus, then use fine focus to sharpen the image.
• What should you do if you need more detail?

  Switch to a higher power objective lens and refocus.
• What is the fifth step of the microscopy practical?

  Observing and measuring the cells.
• What tool is used to measure cell size?

  A graticule (tiny ruler) inside the eyepiece.
• What is the size of one micrometer (µm) in standard form?

  1 µm = 1 × 10⁻⁶ meters.
• What is the sixth step of the microscopy practical?

  Drawing and labelling the cells.
• What should you include in your drawing of the cells?

  Labelled features like the nucleus, cytoplasm, and cell wall.
• What should you write under your drawing?

  The total magnification (eyepiece lens × objective lens).