Using a Light Microscope
- Aim: To use a light microscope to observe, draw and label a selection of plant and animal cells, including a magnification scale
- You will:
- Use a light microscope to make observations of biological specimens and produce labelled scientific drawings
- Include a magnification scale
Preparing a microscope slide
- Specimens must be prepared on a microscope slide to be observed under a light microscope
- This must be done carefully to avoid damaging any biological specimen
- The most common specimens to observe under a light microscope are cheek cells (animal cells) and onion cells (plant cells)
- Stains are used to highlight structures within cells – methylene blue is used to stain cheek cells, iodine for onion cells
Care must be taken to avoid smudging the glass slide or trapping air bubbles under the coverslip
Using a microscope
- Understanding the main features of a light microscope is essential if you are to use it correctly
- Always hold the microscope by the arm when moving it around the lab, and always start your observation with the lowest-powered objective lens
Light microscopes have a lens in the eyepiece which is fixed and two or three objective lenses of different powers
Biological drawings
- Producing biological drawings of what you see under the microscope is a key skill
- The key is not to try to be too artistic with your drawings – they are supposed to be scientific so make sure you follow the rules
Biological drawings should be as large as possible – aim to take up at least half of the space available on the page with your drawings
