Microscopy

Question 1

What are the points in cell theory?

Answer 1

Tissues are made up of cells
Cells are basic unit of all life
Cells only develop from existing cells

Question 2

Define magnification.

Answer 2

How many times bigger an image appears, compared to the real specimen.

Question 3

Define resolution?

Answer 3

Ability of a microscope to distinguish between 2 pints that are close together.

Question 4

Would happen if the resolution was higher?

Answer 4

Clearer the image so more detail can be seen.

Question 5

What does resolution depend on?

Answer 5

Wavelength.

Question 6

What does it mean that light has a long wavelength?

Answer 6

Light microscope= poor resolution.

Question 7

What does it mean that an electron beam has a short wavelength?

Answer 7

Electrón microscope = higher resolution.

Question 8

On most microscopes what magnification is the objective lens?

Answer 8

X4, X10 or X40

Question 9

On most microscopes what magnification is the eye piece lens?

Answer 9

X10

Question 10

How do you work out the total magnification?

Answer 10

Objective lens x eyepiece lens.

Question 11

Why is a stain added when preparing slides?

Answer 11

Adds contrast to help differentiate between the different parts
Makes it visiable by looking 5e structures to be seen

Question 12

What are the safety procedure for a microscope?

Answer 12

Always carry a microscope with both hands taking the weight at the base
Always store microscopes with the lowest power lens in place
Always cover the microscope with a dust sheet when not in use

Question 13

Production of prepared slides: what is the purpose of fixing?

Answer 13

Chemicals are sued to preserve the specimen in as near natural state as possible.

Question 14

Production of prepared slides: what is the purpose of sectioning?

Answer 14

Specimen is dehydrated with alcohol then placed in a wax mould to harden it then sliced very thinly.

Question 15

Production of prepared slides: what is the purpose of staining?

Answer 15

Provides contrast. Different parts of the specimen my take up different stains giving them different colours which the eye can detect.

Question 16

Production of prepared slides: what is the purpose of mounting?

Answer 16

Specimens secured to a microscope slide with a permanent coverslip on top.

Question 17

Why are red blood cells thinner in the middle?

Answer 17

Bicóncavo shape, so mor slight can get through so looks paler.

Question 18

How do atoms form molecules?

Answer 18

Making bonds with each other.

Question 19

Electron: TEM- what re the feature of one?

Answer 19

Electron gun and anode.
Vacuum
Condenser electromagnetic lens
Specimen
Objective electromagnetic lens
Projector electromagnetic lens
Screen or photographic plate.

Question 20

Electron: TEM- what does the electron gun produce?

Answer 20

Beam of electrons

Question 21

Electron: TEM- why does there need to be a vacuum?

Answer 21

No air otherwise it could deflect electrons

Question 22

Electron: TEM- what does the condenser electromagnetic lens do?

Answer 22

Direct the electron beam onto the specimen.

Question 23

Electron: TEM- why is the specimen places on the grid?

Answer 23

Glass slide would stop electrons getting through

Question 24

Electron: TEM- what does the objective electromagnetic lens do?

Answer 24

Produces an image

Question 25

Electron: TEM- why does the projector electromagnetic lenses do?

Answer 25

Focus the magnified image into the screen.

Question 26

Electron: TEM- what does the score or photographic plate do?

Answer 26

Shows the image of the specimen

Question 27

Electron: TEM- how do you get the colour contrast?

Answer 27

Denser parts of the specimen absorb electrons and less dense parts let them through. Where it is topped it is it will be dark where they go through it is white.

Question 28

Electron: TEM- what is the result?

Answer 28

2d black and white image which shows internal detail of the specimen.

Question 29

Electron: TEM- why is the maximum magnification?

Answer 29

Up to 1000000 X

Question 30

Electron: TEM- what is the maximum resolution?

Answer 30

0.5 nm

Question 31

Electron: TEM- what re the limitations?

Answer 31

Needs to be sliced very thinly to allow electrons through. Vacuum- on,y dead specimens.

Question 32

Electron: TEM- what is the grid that the specimen sits on made out of?

Answer 32

Copper

Question 33

Electron: SEM- how do these work?

Answer 33

Scam a beam of electrons across the surface of a specimen nd may reflected electrons are collected.

Question 34

Electron: SEM- what type of image does it give?

Answer 34

3d surface imge

Question 35

Electron: SEM- what type of image does it give?

Answer 35

3d

Question 36

Electron: SEM- what is the maximum magnification?

Answer 36

500000 X

Question 37

Electron: SEM- why is the maximum resolution?

Answer 37

3-10nm

Question 38

Electron: SEM- what are the limitations?

Answer 38

Vacuum, specimens have to be cut thinly so specimen dead.

Question 39

Electron: SEM- why re the advantages compared to the TEM?

Answer 39

Don’t need to be cut quite as thinly as the electrons don’t need to pass through.

Question 40

Electron: SEM- what are the disadvantages compared to the TEM?

Answer 40

Images are lower magnification and resolution

Question 41

Electron: what can staining be used on?

Answer 41

Heavy metal alts such as lead.

Question 42

Electron: how does the staining work?

Answer 42

Attach to some parts of the specimen and not others. He y metal ions scatter the electrons that are fired at the sample giving contrast between the structures.

Question 43

Electron: how are the images produced in staining, what can be can be changed and how?

Answer 43

Black and white. Colour can be added after- false colour to make them easier to see and interpret.