B1.1.4 - Electron Microscopy

Question 1

Define: Resolution

Answer 1

Smallest distance between 2 points that are considered different entities

Question 2

Name the two types of electron microscopy

Answer 2

• TEM (transmission electron microscope)
• SEM (scanning electron microscope)

Question 3

Explain TEM

Answer 3

TEM examines cells and tissues in thin slices or sections
It has revealed sub cellular structures not visible in light
Maximum magnification is around x1,000,000

Question 4

Explain SEM

Answer 4

SEM has a large field depth and can see surface structures

Question 5

How is greater resolution achieved?

Answer 5

By using beams of high energy electrons as the light source

Question 6

Magnification Formulas

Answer 6

Total Mag = Eyepiece lens x Objective lens

Size Image = Actual Size x Magnification

Question 7

Name 6 differences in light and electron microscopy

Answer 7

1) Light Microscopes are cheap to buy and operate but Electron Microscopes are expensive
2) Light Microscopes are small and portable but Electron Microscopes are big and difficult to move
3) Light Microscopes can quickly prepare samples but Electron Microscopes can take days
4) Light Microscopes are seen in natural colour but Electron Microscopes are black and white only
5) Light Microscopes can see living & dead specimen but Electron Microscopes can only see dead
6) Light Microscopes have lower resolution compared to Electron Microscopes, w/ a very high one