Microscopes

Question 1

What is magnification?

Answer 1

Magnification is a measure of how many times bigger the
The image is larger than the object

Question 2

What is resolution?

Answer 2

the smallest distance between two points that can still be seen as two separate points

Question 3

Advantages and Disadvantages of Light Microscopes.

Answer 3

Advantages
Can see living plants and animals or parts of them. This allows you to compare prepared slides with living tissue.

Relatively cheap so they are used in schools, universities, hospitals,
industrial labs and research labs.

Light and portable, so you can use them almost anywhere, e.g., identifying malaria in the field.

Disadvntages
Preserving and staining tissue produces artefacts. These are not actual parts of the living tissue. They are a result of the process of preserving and staining.

Limited power of resolution magnification.

Question 4

Advantages and Disadvantages of Electron Microscopes.

Answer 4

Advantages
Huge power of magnification and resolution.Can identify many details of cell structure

Disadvantages
All specimens are examined in a vacuum – air
would scatter electrons and produce a blurred
image. So all samples are non-living.

Specimens undergo severe treatment that is
likely to produce artefacts. Preparing samples is
demanding is requires skill.

Extremely expensive.

EM are very large and must be kept at a
constant temperature and pressure, and with
an internal vacuum. They are quite expensive.

Question 5

Give examples of stains

Answer 5

❑ Methylene blue: stains the nuclei of animal cells blue

❑ Orcein: stains chromosomes in dividing nuclei of animal

and plant cells reddish-brown

❑ Iodine: stains starch-containing material (and
amyloplasts) in plant cells blue-black.