Microscopy

Question 1

Resolution

Answer 1

The ability to distinguish between two sperate points

Question 2

Magnification

Answer 2

how many times larger the image of a specimen observed is, in comparison to the actual size of the specimen

Question 3

Magnification equation

Answer 3

Magnification = Image size / Actual size

Question 4

Staining

Answer 4

Provides contrast to distinguish between different structure in the sample

Question 5

Differential staining

Answer 5

When multiple stains are used.
Each stain binds to a specific cell structure, so the structures can be easily identified.

Question 6

Stain that binds to DNA and stains chromosomes dark red

Answer 6

Acetic orcein

Question 7

Stain that stains cytoplasm dark red or purple

Answer 7

Eosin

Question 8

Stain that stains starch blue/black

Answer 8

Iodine (violet under microscope)

Question 9

Stain that stain cellulose yellow

Answer 9

Iodine in potassium iodide solution

Question 10

Stain that stains RNA/DNA a purple/blue colour

Answer 10

Haemtoxylin

Question 11

All-purpose stain that is used to stain DNA blue

Answer 11

Methylene blue

Question 12

Crystal violet / Methylene blue

Answer 12

Positively charged
Attract and stain negatively charged materials

Question 13

Nigrosin / Congo red

Answer 13

Negatively charged
Cannot enter cells as cytosol repels them
Stains background

Question 14

Gram staining

Answer 14

Gram-positive bacteria appear blue/purple (as stain is reduced to thicker peptidoglycan cell wall later absorbing the dye)
Gram-negative bacteria cannot absorb crystal violet stain as cell wall is too thin.

Safranin used as a counterstain - turns them red.

Question 15

Benefit of gram-staining

Answer 15

Helps medics prescribe the correct antibiotics

Question 16

Dry mount

Answer 16

Thin slices
Just a coverslip on top

Question 17

What is a dry mount used for

Answer 17

Plant tissue

Question 18

Wet mounts

Answer 18

Water added to specimen
Lower coverslip with mounted needle to prevent air bubbles

Question 19

What are wet mounts used for

Answer 19

Aquatic organism

Question 20

Squash slides

Answer 20

Wet mount
Push on coverslip to squash sample.
Ensures s thin layer for light to pass through

Question 21

What are squash slides used for

Answer 21

E.g. Root tip

Question 22

Smear slides

Answer 22

Use edge of another slide to smear sample across slide.
Creates smooth, thin, even coated specimen.
Coverslip on top

Question 23

What are smear slides used for

Answer 23

Blood cells

Question 24

What microscope are these mounts used for

Answer 24

Light / optical

Question 25

Scientific drawing rules

Answer 25

Pencil Title State magnification Annotate components No sketching No shading 50% of page Label lines parallel to top of paper

Question 26

What is an eyepiece graticule?

Answer 26

Scale on a glass disc inside light microscopes Used to measure the size of objects under microscopes. (Needs calibrating each time you change the objective lens and magnification)