Required Practical: Microscopy

Labelling a Microscope

Preparing and Observing Slides

Slide Preparation: Viewing Onion Cells

• Start with a clean microscope SLIDE.
• Add a single DROP OF WATER to the slide.
• Carefully cut an onion and separate it into layers.
• With TWEEZERS, peel off a piece of the EPIDERMAL tissue and place it onto the drop of water on your slide.
• Add a drop of IODINE SOLUTION as a stain to highlight cell features.
• Place a COVER SLIP over the specimen carefully to avoid air bubbles which can obstruct the view.

Using a Light Microscope

• Secure the slide on the stage of the microscope.
• Begin with the LOWEST-POWERED OBJECTIVE LENS.
• Adjust the COARSE ADJUSTMENT KNOB to bring the stage close to the lens without it touching.
• Look through the EYEPIECE and use the COARSE ADJUSTMENT KNOB to find the focus.
• Fine-tune the focus with the FINE ADJUSTMENT KNOB for a clear image.
• For greater detail, switch to a higher-powered objective lens and refocus.

Drawing Observations

• Draw what you observe with a PENCIL.
• Ensure the drawing occupies at least half of the space provided.
• Use clear, UNBROKEN LINES, and avoid colouring or shading.
• Draw cells proportionally, labelling important features like the nucleus or chloroplasts with straight lines.
• Include a TITLE and the MAGNIFICATION LEVEL.