Microscopy

Question 1

How is a wet mount prepared?

Answer 1

-place a drop of water on a slide -place the specimen on top -carefully tilt and lower a coverslip ensuring no air bubbles are trapped

Question 2

How can stain be added to a wet mount?

Answer 2

-a drop of stain is placed next to one edge of the cover slip -put a bit of paper towel on the opposite side, this will draw the stain across the specimen

Question 3

Which two types of microscope require stains to be used?

Answer 3

Light microscopes and TEMs

Question 4

i) What is used to stain nucleic acids? ii) What colour are they stained?

Answer 4

i) Methylene blue ii) blue

Question 5

Name two common light microscope stains

Answer 5

Methylene blue and Eosin

Question 6

What does eosin stain?

Answer 6

Eosin stains the cytoplasm pink

Question 7

i) What does Haemotoxylin stain? ii) What colour does it go?

Answer 7

i) Nuclei ii) Blue-purple or black

Question 8

What is toulidine used to stain?

Answer 8

Phloem and xylem, phloem is stained red and xylem is stained green-blue

Question 9

What is used as a stain for TEM images?

Answer 9

Heavy metals e.g lead

Question 10

How do heavy metals act as stains for electron microscopes?

Answer 10

the metal ions scatter the electrons which creates contrast

Question 11

Name 4 different types of microscope

Answer 11

-light microscope -laser scanning confocal microscope -transmission electron microscope -scanning electron microscope

Question 12

What is the maximum magnification of a light microscope?

Answer 12

x1500

Question 13

What is the resolution of a light microscope?

Answer 13

200nm (0.2 micrometres)

Question 14

What is the maximum magnification of a laser scanning confocal microscope?

Answer 14

x1500

Question 15

What is the resolution of a laser scanning confocal microscope?

Answer 15

200nm (0.2 micrometres)

Question 16

What are laser scanning confocal microscopes used for?

Answer 16

Looking at thick specimens at different depths

Question 17

How does a TEM work?

Answer 17

-an electron beam passes through a very thin sample -the denser parts of the specimen absorb more electrons, making it appear darker and providing contrast

Question 18

What is the max. magnification of a TEM?

Answer 18

x500,000

Question 19

What is the max resolution of a TEM?

Answer 19

0.5nm

Question 20

How does a SEM work?

Answer 20

-a beam of electrons are moved across the specimen -electrons are knocked off the specimen -these electrons are gathered in a cathode ray tube to form an image -the image produced is of the surface of the specimen

Question 21

What is the max. magnification of a SEM?

Answer 21

x100,000

Question 22

What is the max resolution of a SEM?

Answer 22

3-10 nm

Question 23

What does SEM stand for?

Answer 23

Scanning electron microscope

Question 24

What does TEM stand for?

Answer 24

Transmission electron microscope

Question 25

Define magnification

Answer 25

the number of times greater an image is than the object

Question 26

Define resolution

Answer 26

the ability to distinguish two separate points as distinct from each other

Question 27

How is magnification calculated?

Answer 27

Image size/ actual size

Question 28

How is overall magnification calculated?

Answer 28

objective lens x eyepiece lens

Question 29

How do you convert from 1mm to nm?

Answer 29

x10⁶

Question 30

How do you convert from nm to µm?

Answer 30

x1000

Question 31

How many µm are there in 1mm?

Answer 31

1000

Question 32

What colour is the background of an SEM image?

Answer 32

Black

Question 33

Are light microscope images 2D?

Answer 33

Yes

Question 34

Are TEM images 3D?

Answer 34

No they are always 2D

Question 35

Are SEM images 2D?

Answer 35

Yes, however they can be processed by a computer to give a 3D image

Question 36

Are LSCM images 3D?

Answer 36

Yes

Question 37

What colour background does a light microscope image have?

Answer 37

White

Question 38

Does a TEM image have a black background?

Answer 38

No it is white

Question 39

What colour is the background for a LSCM image?

Answer 39

Black

Question 40

How does a compound light microscope work?

Answer 40

- There are two lenses, one objective, the other the eyepiece lens - The objective lens magnifies the specimen , the eyepiece lens further magnifies this