Microscopy

Question 1

What is a stage micrometer

Answer 1

a microscope slide with an accurate measuring scale

Question 2

What is a stage micrometer used for

Answer 2

calibrate the value of the eyepiece divisions at different magnifications.

Question 3

How to calibrate an eyepiece graticule

Answer 3

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.

Question 4

What does iodine stain

Answer 4

Starch

Question 5

What does methylene blue stain

Answer 5

DNA

Question 6

Wet mount technique

Answer 6

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. What

Question 7

What do you need to be careful with in a wet mount

Answer 7

make sure the stain used is not toxic to the live specimen

Question 8

Dry mount technique

Answer 8

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