B1.1.3 - Light Microscopy

Question 1

How does a light microscope work?

Answer 1

Light is passed through the object on slide, then through 2 glass lenses, the objective and eyepiece lens.

Question 2

How do you observe through a light microscope?

Answer 2

1) Move Stage to lowest position
2) Objective lens, lowest magnification
3) With the cell on, place the slide on the stage
4) Raise the stage to the highest position, making sure the slide doesn’t touch the lens
5) Slowly lower stage w/ coarse focus knob until you can just see it
6) Turn fine focus knob slowly until object is now clear
7) For greater detail, switch to higher magnification objective lens

Question 3

Why do we stain cells?

Answer 3

Many cells are colourless, so staining can let us see the whole thing or highlight certain parts of

Question 4

Name some common stains

Answer 4

Methylene blue, iodine, crystal violet

Question 5

Which one makes it easier to see the nucleus?

Answer 5

Methylane Blue

Question 6

What does iodine do?

Answer 6

Makes it easier to see plant cell nuclei

Question 7

Which one stains bacteria cell walls?

Answer 7

Crystal violet

Question 8

How do you apply a stain?

Answer 8

1) Place cells on a glass slide
2) Add one drop of stain
3) Place coverslip on top
4) Tap gently with a pencil to remove air bubbles