Required practical: microscopy of plant and animal cells

Prepare the wet mount

Follow the preparation in order so the specimen is ready for clear observation.

1. 1Water on the slidePlace a drop of water on the slide before adding the specimen.
2. 2Specimen lies flatAdd a thin layer of the specimen and lay it flat so it can be viewed through the light microscope.
3. 3Add the stainUse iodine solution for plant cells or methylene blue for animal cells because staining makes structures easier to see.
4. 4Coverslip goes downLower the coverslip onto the specimen at an angle to reduce the chance of trapping air bubbles.+

Focus the microscope safely

The direction of coarse focusing matters: close from the side first, then move away while looking through the eyepiece.

1. 1Start on low powerBegin with the lowest-power objective lens positioned over the specimen.
2. 2Move close from the sideWith the low-power objective selected, look from the side and use the coarse adjustment to move the objective close to the slide without touching it.
3. 3Focus moving awayNow look through the eyepiece and use the coarse adjustment to move the objective slowly away from the slide until the specimen comes into focus.
4. 4Sharpen the imageUse the fine adjustment to sharpen the focused image.
5. 5Switch to higher powerChange to a higher-power objective when you want to see more detail.
6. 6Fine focus onlyRefocus with the fine focusing knob rather than the coarse adjustment because the shorter working distance increases the risk of the objective contacting the slide.

Magnification

magnification = size of image ÷ size of real object

Compare how large the image appears with the real object to calculate how many times it has been magnified.

Use matching units such as mm or µm before dividing; magnification is a ratio and has no unit.

Practical toolkit

Know what each item or term contributes to the microscopy practical.