Microscopy

Question 1

How to prepare a microscope slide

Answer 1

1) Use a dropping pipette to put a drop of water onto a glass side.
2) Separate one of the thin layers of the onion using a mounting needle/scalpel.
3) Peel off a thin layer of epidermal tissue from the inner surface.
4) Use a forceps to put this thin layer onto the drop of water you’ve placed on the microscope slide. Ensure the layer of onion cells is flat on the side.
5) Put 2-3 drops of iodine solution onto the onion tissue.
6) Lower a coverslip onto the slide, do this by placing one edge of the coverslip on the slide at a 90 degrees angle and use the mounted needle to lower the other edge onto the slide.
7) Use a piece of blotting paper to soak any excess liquid on the slide.
8) Put the prepared slide on the microscope stage.

Question 2

How to use a light microscope

Answer 2

1) Carry the microscope with one hand under the base and one hand on the arm.
2) Plug in and switch on the light source.
3) Clip in the prepared slide to the stage.
4)Select the lowest power objective lens first.
5) Look down on the eyepiece lens.
6)Turn the coarse focus(adjustment wheel) to move the stage upwards and get a rough image.
7) Turn the fine focus(adjustment) wheel to get a more precise image.
8) Select the medium power objective lens and repeat steps 5-6.

Question 3

Advantages of using an electron microscope instead of a light microscope

Answer 3

Electron microscopes have a higher magnification and resolution than light microscopes.

Question 4

Why do scientists add a stain when preparing a slide?

Answer 4

Most cells are transparent, without a stain you wouldn’t see the parts of the cell

Question 5

Why is a drop of water needed when preparing a slide

Answer 5

Water prevents the cell from drying out

Question 6

Why is the coverslip slowly lowered at 90 degrees angle?

Answer 6

This minimizes air bubbles

Question 7

Why are onion cells thin?

Answer 7

So light gets through the sample, to get an image through the microscope