PAG 01 microscopy

Question 1

What is an eyepiece graticule?

Answer 1

NO UNITS. glass disc found in the eyepeice marked 1-100

Question 2

What is a stage micrometer?

Answer 2

Microscope slide with a very accurate scale of 1 division is 10um or 0.01mm

Question 3

How does one calibrate a light microscope?
(5 steps)

Answer 3

1. Choose an objective lense
   2.put the stage micrometer and eyepeice graticule in place
2. get the scale in clear focus
3. Align the two scales and take a reading from each
   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

Differential staining

Answer 4

This provides contrast to distinguish between different structures in the sample.
Differential staining is when multiple stains are used, and each stain binds to a
specific cell structure, staining each structure differently so the structures can be easily
identified.

Question 5

Wet mount

Answer 5

this is used for a variety of live specimens, such as aquatic animals

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 specime

Question 6

Dry mount

Answer 6

this is used for specimens such as hairs, parts of insects, pollen, parts of
flowers etc.

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 7

Drawings from a microscope rules

Answer 7

● No shading. Areas that should be shaded should be labelled instead.
● The drawing should take up at least half of the page.
● Label lines must be completely horizontal, drawn with a ruler, exactly touch the
object that they’re labelling and must not overlap each other.
● Drawing lines should completely connect and should not be hairy.
● A scale should be given e.g. for the magnification of the image size.
● They should be drawn in pencil and look like the actual image.

Question 8

stain: Acetic orcein

Answer 8

binds to DNA and stains
chromosomes dark red

Question 9

Stain: Eosin

Answer 9

stains cytoplasm dark red or pink

Question 10

Stain: Iodine

Answer 10

stains starch blue-black (appears
violet under the microscope)

Question 11

Stain: Iodine in potassium iodide solution

Answer 11

stains cellulose yellow

Question 12

Stain: Haematoxylin

Answer 12

stains RNA/DNA a purple/blue colour

Question 13

Stain: Methylene blue

Answer 13

is an all-purpose stain, used often to stain DNA blue