Microscopy

Question 1

Disadvantages of an electron microscope:

Answer 1

• Can only observe a dead specimen as it has to be observed in a vacuum and will die as there is no oxygen
• Expensive - £1 million
• Have to have training to use it
- expert preparation
• (Maintenance costs)
• Black and white (but can add artificial colouring)
• Attached by magnetic fields
• Can’t use phone in the same room

Question 2

Advantages of an electron microscope:

Answer 2

• Using a beam of electrons instead of a beam of light allows the electron microscope to gain a much higher resolution in seeing much smaller objects e.g
• Higher magnification (up to x2,000,000)
• Higher resolution (0.1 nm)
• Can see inside of the cell - better for observing details

Question 3

Advantages of an electron microscope:

Answer 3

• Higher magnification (up to x2,000,000)
• Higher resolution (0.1nm)
• Can see inside of the cell - better for observing details
• Using a beam of electrons instead of a beam of light allows the electron microscope
to gain a much higher resolution in seeing much smaller objects e.g.
mitochondria, chloroplasts, ribosomes, plasmids

Question 4

Disadvantages of light microscope:

Answer 4

• Lower magnification (around x200)
• Lower resolution(200nm)
• Can only see the outside of the cells and nucleus

Question 5

Advantages of light microscope:

Answer 5

• Mobile/portable
• Colour
• Can view a living specimen
• Cheaper - £200 - £300
• No complex lighting system needed
• With light microscopes large sub cellular structures can be
seen

Question 6

Magnification:

Answer 6

the ability of a lens or other optical instrument to magnify (enlarge) the size of something in an optical image

Question 7

Total magnification:

Answer 7

Total magnification = magnification
of eyepiece (fixed 10x) x magnification of objective lens (4x,
10x, 14x)

Question 8

What is resolution?

Answer 8

the level of detail contained in an image

Question 9

What are the two types of electron microscope?

Answer 9

• Scanning Electron Microscope
(SEM)
• electrons scan the surface of a sample

• Transmission Electron
Microscope
• electrons penetrate a sample - can see inside a sample

Question 10

Explain how electron microscopy has increased understanding of sub-
cellular structures:

Answer 10

• An electron microscope has a much higher magnification and resolving power
• This means it can be used to study cells in much more detail
• Scientists can now see (and better understand) sub-cellular structures