Microscopy

Question 1

Outline how a student can prepare a temporary mount of tissue

Answer 1

Obtain a thin slice of the plant tissue

Add a droplet of water on the plant tissue

Add a stain on each side to make the structures visible

Place the coverslip at a 45 degree angle to prevent air bubbles

Question 2

How do light microscopes work

Answer 2

Lenses focus rays of light and magnifies the image
Different structures of the cell absorbs different wavelengths and amounts if light

Transmits light to the observer via objective lens + eyepeice

Question 3

TEM

Answer 3

Transmission electron microscope
- Transmits a high beam of electrons through a specimen producing an image
Denser parts appear darker

Question 4

SEM

Answer 4

Focuses a beam of electrons along a specimens surface using an electromagnetic lens
Electrons knock off other electrons producing an image
- Produces a 3D image

Question 5

Describe how a confocal microscope works

Answer 5

Focuses a laser beam onto a small sample’s surface area using an objective lens

Laser causes fluroscent dye to give off light ,an image is produced pixel by pixel

Question 6

Formulae

Answer 6

A = I/M

Question 7

Magnification and resolution definition

Answer 7

Magnification - factor by which the image is larger than the actual specimen

Resolution- smallest seperation by which 2 structures can be distinguished from each other

Question 8

Why do samples need to be stained

Answer 8

To be much more easily distinguishable as the contrast between lighter and darker areas , makes it easier to distinguish

Different absorption and wavelengths

Coloured dye also binds to the structuees

Question 9

Explain how to use an eyepeice graticule and stage micrometer to measure the size of a structure

Answer 9

Place the micrometer onto the graticule snd line them up

Count how many graticule divisions are on the 100um micrometer

Length of 1 eyepeice division = 100um/divisions

Use calibrated values to discover the actual length of the structures