Microscopy (not finished)

Question 1

Magnification Definition

Answer 1

Number of times larger an image appears when compared to the actual specimen

Question 2

What is maximum magnification of Light Microscope

Answer 2

x1500

Question 3

Resolution Definition

Answer 3

The ability to distinguish between 2 separate points

Question 4

What is the limit of resolution

Answer 4

Wavelength/2

Question 5

Max resolution of Light Microscope and Confocal Laser Scanning Microscope

Answer 5

200nm (Light wavelength in 400nm)

Question 6

Why is Electron Microscope Resolution higher

Answer 6

Uses beam of electrons which has shorter wavelength

Question 7

Why do we preserve specimens

Answer 7

-Enables them to be cut into sections for observation
-Enables them to be treated with different stains

Question 8

Function of the eyepiece in an LM

Answer 8

-Magnifies but does not resolve
-Can be dismantled to insert eye piece graticule

Question 9

Function of Barrel in LM

Answer 9

Passes light from objective lens to eyepiece

Question 10

Function of Turret in LM

Answer 10

-Holds objective lenses
-Rotates to enable selection of objective lens

Question 11

Function of objective lens

Answer 11

Magnifies and resolves specimen

Question 12

Function of Stage in LM

Answer 12

-Supports slide in correct position
-Enables light to pass through specimen

Question 13

Function of Condenser in LM

Answer 13

Focuses light from illuminator source onto specimen

Question 14

Function of Iris diaphragm in LM

Answer 14

-Controls level of light reaching specimen
-Best definition achieved with lower light intensity

Question 15

Function of Substage illuminator in LM

Answer 15

-Source of illumination
-Blue light bulb can be used to use light of shorter wavelength to improve resolution

Question 16

How to prepare a temporary slide for observing using LM

Answer 16

Fixation - use 70% alcohol
Staining - use few drops of appropriate differential stain
Mounting - Cover with coverslip to exclude dust and air

Question 17

What are advantages of temporary slide preparation

Answer 17

-Rapid and simple procedure
-Can mount specimen to glycerine to prolong examination period

Question 18

What are the 7 stages of preparing a permanent slide for LM

Answer 18

1. Fixation
2. Dehydration
3. Clearing
4. Embedding
5. Sectioning
6. Differential Staining
7. Mounting

Question 19

Why do we do fixation in preparation of permanent slide for LM

Answer 19

-Preserves specimen in lifelike condition
-Minimised distortion
-Chemicals such as alcohol or acetic acid are added to make proteins and nucleic acids insoluble –> Fixing them in position

Question 20

Why do we do dehydration in preparation of permanent slide for LM

Answer 20

-Removes traces of water from fixed material
-Achieved by placing the specimen in increasing concentration of alcohol (up to 70%)

Question 21

Why do we do clearing in preparation of permanent slide for LM

Answer 21

-Addition of xylol removes dehydrating alcohol
-Ensures material is made transparent

Question 22

Why do we do embedding in preparation of permanent slide for LM

Answer 22

-Supports material so it is firm enough for sectioning
-Can be resin, plastic or wax

Question 23

Why do we do Sectioning in preparation of permanent slide for LM

Answer 23

-Use a microphone to cut fine slices embedded specimen
-So that light can pass through the specimen

Question 24

Why do we do Differential Staining in preparation of permanent slide for LM

Answer 24

-Improves contrast between different tissues and/or structures
-Can be permanent or temporary

Question 25

What four stains can be used for a plant specimen

Answer 25

Iodine -Kl solution Aniline sulfate Eosin Toludine

Question 26

What three stains can be used for animal specimen

Answer 26

Methylene blue Leishman's stain Haematoxylin

Question 27

What are the advantages of using differential stains

Answer 27

-Easier to observe -When plant--> allows distinguishment between chemicals enabling identification of different tissues. -When animal--> allows distinguishment between different types of WBC -Improves contrast between structures (and cells)

Question 28

Why do we do Mounting in preparation of permanent slide for LM

Answer 28

-Embeds and protects material -Ensures material can be observed over a long period of time

Question 29

what are advantages of Light Microscopes

Answer 29

Low skill set required Can be transported to use in field work Can observe living organisms Relatively inexpensive so available for schools and colleges

Question 30

Disadvantages of LM

Answer 30

Low resolution Hence limited magnification Many internal cellular structures can be seen

Question 31

What are the two Romanowsky stains

Answer 31

Leishman's Wright's

Question 32

What colour are red blood cells (erythrocytes) on Leishman's stain?

Answer 32

Red to yellowish red

Question 33

What colour are Neutrophils on Leishman's stain?

Answer 33

Dark purple nuclei, pale pink cytoplasm, reddish-lilac small granules

Question 34

What colour are Eosinophils on Leishman's stain?

Answer 34

Blue nuclei, pale pink cytoplasm, red to orange-red large granules

Question 35

What colour are Basophils on Leishman's stain?

Answer 35

Purple to dark blue nucleus, dark purple cytoplasm, dark large granules

Question 36

What colour are lymphocytes on Leishman's stain?

Answer 36

dark purple to deep bluish purple nuclei, sky blue cytoplasm

Question 37

What colour are Platelets (thrombocytes) on Leishman's stain?

Answer 37

Violet

Question 38

What colour are parasites on Leishman's stain?

Answer 38

Dark blue

Question 39

What are the key points (6) of cell theory

Answer 39

-A cell is the basic unit of all life forms -All living organisms are made up of one or more cells -Metabolic processes -All new cells are derived from pre-existing cells -Cells possess genetic material which can be passed on to their daughter cells -A cell is the smallest unit of an organism capable of surviving independently.

Question 40

Impacts of microscopes on biology

Answer 40

-Enables scientists to see and examine cells in detail -Opened up new fields of science