Microscopy

Question 1

How does a light microscope work?

Answer 1

Light microscopes use light and lenses to form an image of a specimen and magnify it.

Question 2

How does an electron microscope work?

Answer 2

Electron microscopes use electrons instead of light to form an image of a specimen and magnify it.

Question 3

What do light microscopes show you?

Answer 3

They let us see individual cells and large subcellular structures.

Question 4

What do electron microscopes show you?

Answer 4

They let us see much smaller things in more detail, like the internal structure of mitochondria and chloroplasts. They even let us see smaller things like ribosomes and plasmids.

Question 5

What is the difference between electron microscopes and light microscopes?

Answer 5

Electron microscopes have a higher magnification and resolution.

Question 6

What is the equation for magnification?

Answer 6

Magnification = image size / real size

Question 7

What do you divide by to convert micrometers (um) into millimetres (mm)?

Answer 7

You divide by 1000.

Question 8

How do you prepare your slide in a microscope practical to look at onion cells?

Answer 8

You first add a drop of water to the middle of a clean slide.

Then you cut up an onion and separate out into layers, use tweezers to peel off some epidermal tissue from the bottom of one of the layers.

Using the tweezers, place the epidermal tissue into the water on the slide.

Then add a drop of iodine solution. Iodine solution a stain. Stains are used to highlight objects in a cell by adding colour to them.

Place a cover slip on top. To do this stand the cover slip upright on the slide next to the water droplet then carefully tilt and lower it so it covers the specimen. This is so no air bubbles get trapped in there and make your view blurry.

Question 9

What are the 6 parts of a light microscope?

Answer 9

Ey’epiece, coarse adjustment knob, fine adjustment knob, High and low power objective lenses, light, and stage.

Question 10

What are the steps of using a light microscope to look at your slide?

Answer 10

First, you clip the slide you’ve prepared onto the stage.

Select the lowest powered objective lens

Use the course adjustment knob to move the stage up to just below the objective lens.

Then, look down the eyepiece. Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus.

Adjust the focus with the fire adjustment knob until you get a clear image of what’s on the slide.

If you need to see the slide with greater magnification, swap to a higher powered objective lens and refocus.