Microscopy

Question 1

Light (optical) microscope

Answer 1

Radiation used: Light rays
Max magnification: ~ 1500 times
Resolution: 200nm
Size of microscope:Small and portable
Cost:~£100 for a school one

Question 2

Electron microscope

Answer 2

Radiation used:Electron beams
Max magnification: 2 000 000 times
Resolution:0.2nm
Size of microscope:Very large and not portable
Cost:Several £100,000 to £1 million plus

Question 3

Comparison between light and electron microscope

Answer 3

Electron microscopes have a higher magnification and resolution than light microscopes. This means that scientists can see more sub- cellular structures (structures within the cells).

Question 4

What does a light microscope let us see?

Answer 4

Light microscopes image
can let us see structures like nuclei and mitochondria.

Question 5

What does a electron microscope let us see?

Answer 5

Electron microscopes image
can let us see the internal structures of a chloroplast and mitochondrion.

Question 6

Magnification formula

Answer 6

size of image/real size of object

Question 7

Microscopy practical

Answer 7

Making a wet mount slide e.g. onion cells
Place a thin section of the specimen onto slide.
Place a drop of water in the middle of the slide or stain the specimen.
Gently lower cover slip onto the specimen without trapping air bubbles.

Soak up any excess liquid with a paper towel.
Switch on the light source and place your slide on the stage.
Use the lowest objective lens and turn the focusing wheel to move the lens close to the slide.
Slowly adjust the focusing wheel until you can see a clear image.
Increase the magnification by changing the objective lens and re-focus.

Question 8

Drawing what you see

Answer 8

Clear line drawing – no shading
Label main cell structures
Add a title and the magnification.