Biology: Microscopes

Question 1

Optical Microscopes

Answer 1

• Allows us to see large organelles but not in fine detail
• Above the magnification of x1500 is not clear
• The wavelength is reliably long
• Objects that are close together will apart as one
• Specimens need to be stained

Question 2

Transmission Electron Microscopes (TEM)

Answer 2

• Parts of the specimen that absorb the electrons appear darker
• Image is 2D but can be developed to 3D

LIMITATIONS:
- A vacuum is needed so living specimens cannot be viewed
- Staining samples is complicated and even then only a black and white image is produced
- Specimen must be esprememtly thin

Question 3

Scanning Electron Microscopes (SEM)

Answer 3

• Specimen doesn’t need to be extremely thin
• 3D space can be built up using computer analysis of the pattern of scattered electrons
  LIMITATIONS:
• A vacuum is needed so living specimens cannot be viewed
• The image may contain artifacts as a result of the way the specimen was prepared
• Has a low resolving
• Staining is complicated and even then only a black and white image is produced however “false-colour” can be added to after using computer software