Set 8 – Microscope Experiments and Cell Investigations

What is the first step when using a light microscope?

Lower the stage.

Which objective lens should be used first?

The lowest power objective lens.

Which focusing knob should be used first?

Coarse focus.

Which focusing knob is used to sharpen the image?

Fine focus.

What should you do before changing to a higher power objective lens?

Lower the stage to avoid damage.

What is the purpose of a coverslip?

Holds the specimen in place and protects the lens from liquid.

Why is a coverslip lowered at a 45 degree angle?

To prevent air bubbles forming.

Why is water added when preparing a slide?

To prevent cells drying out.

Why is a stain added to a specimen?

To make cell structures easier to see.

What stain is used for onion cells?

Iodine solution.

What stain is used for cheek cells?

Methylene blue.

How are onion cells collected?

Remove a thin layer of cells from between onion leaves using forceps.

How are cheek cells collected?

Swab the inside of the cheek using a cotton bud.

Where are collected onion cells placed?

On a glass slide.

Where are collected cheek cells placed?

On a glass slide.

What structure becomes more visible after staining?

The nucleus.

Why does the nucleus appear darker after staining?

It absorbs the stain.

What is the final step when preparing onion or cheek cells for observation?

Lower the coverslip and view under the microscope.