Microscopes

Question 1

Principles of light microscopes (4)

Answer 1

• visible light passes through specimen
• into magnifying lens
• into objective lens
• into eye

Question 2

Limitations of optical microscopes (2)

Answer 2

• Low resolution because the resolution of light is 200nm so smaller objects cannot be viewed. properly. Cannot be used to properly study ribosomes, endoplasmic reticula, and lysosomes.
• Low magnification because the maximum magnification is x1500 magnification beyond this is useless because of the low resolution

Question 3

Principles of TEM (4)

Answer 3

• electron beam through a sample
• 2D image is formed using electromagnets
• denser tissue appears darker in the micrograph as electrons are more easily absorbed
• less dense regions the electrons can easily pass through, making them appear lighter

Question 4

Advantages of TEM (2)

Answer 4

-High resolution images are produced.
-Thus, small objects can be displayed.

Question 5

Limitation of TEM (2)

Answer 5

-Can only be used on thin specimens.
-the microscope can only work with non-living specimens in a vacuum

Question 6

Limitation of SEM

Answer 6

-lower resolution images given.
- only on non-living specimens, it can be used upon.