PAG 1 - Microscopy

Question 1

Preparing solides:

Answer 1

1. Staining
2. Mount sample

Question 2

Binds to DNA and stains chromosomes dark red

Answer 2

Acetic orcein

Question 3

Stains cytoplasm dark red / pink

Answer 3

Eosin

Question 4

Stains starch blue-black

Answer 4

Iodine

Question 5

Stains cellulose yellow

Answer 5

Iodine in potassium iodine solution

Question 6

Stains RNA/DNA a purple/blue colour

Answer 6

Haematoxylin

Question 7

All purpose stain, DNA blue

Answer 7

Methylene blue

Question 8

Wet mount

Answer 8

a) Use a pipette to put a drop of water on the slide.

b) Use tweezers to place the specimen in the water.

c) Put the cover slip on by standing it upright on the slide, next to the water droplet,
then carefully tilt it down onto the specimen. Be careful to not add bubbles – these
will obstruct the view of the image.

d) Add a stain. Put a drop on one edge of the cover slip. Put a paper towel on the opposite edge. The paper towel will absorb the stain, drawing it under the coverslip, staining the specimen. (You want to make sure the stain used is not toxic to the live specimen).

Question 9

Dry mount:

Answer 9

a) Slice the specimen into a thin piece so light can pass through

b) Use tweezers to pick it up and put it in the middle of the slide

c) Put a cover slip on top of it.

Question 10

Calibrating a microscope:

Answer 10

1. Set up the microscope to the required magnification to view the sample.
2. Place a stage graticule on the stage.
3. Line up the two scales (the stage and eyepiece graticules) similar to the diagram.
4. Count the number of divisions on the eyepiece graticule equivalent to each division
   on the stage micrometre.
5. As the length equivalent to each division on the stage micrometer are known, it is
   possible to calculate the length of one eyepiece division.