Lesson 3- Light Microscopy. Flashcards
Explain how a light microscope works.
The microscope passes light through an object placed on a slide on the stage, then through two glass lenses - the objective lens and the eyepiece lens, which magnify the object.
State the instructions that will help one use a light microscope.
1: Move the stage to its lowest position.
2: Select the objective lens with the lowest magnification.
3: Place the slide, which has cells on it, on the stage.
4: Raise the stage to its highest position, taking care that the slide does not touch the lens.
5: Lower the stage slowly using the coarse focus knob until you see your object (it will normally be blurred).
6: Turn the fine focus knob slowly until your object comes into clear focus.
7: To see the cells in greater detail, switch to a higher magnification objective lens without moving the stage. Use the fine focus knob to bring the object into clear focus again.
Name all parts need for the success of the light microscope.
Coarse focus/fine focus/eyepiece lens/objective lens/stage/slide/light source.
When should you use the stain Methylene Blue?
When you want to see the nuclei of an animal cell easier.
When should you use the stain Iodine?
When you want to see the nuclei of plants better.
When should you use the stain Crystal Violet?
When you want to see the bacterial cell walls better.
How should one apply a stain?
1: Place the cells on a glass slide.
2: Add one drop of stain.
3: Place a coverslip on top.
4: Tap the coverslip gently with a pencil to remove air bubbles.
Why do scientists use stains?
They stain cells, which are normally colourless, in order to see them better.
