PAGs

Question 1

Test for protein

Answer 1

Biuret test
add sodium hydroxide so a layer is formed on top
then add copper sulfate solution
Observe colour change

Question 2

Protein colour change

Answer 2

Blue to purple

Question 3

Test for reducing sugar

Answer 3

Add Benedict’s reagent
Place in (thermostatically controlled) water bath for 2 mins
Observe colour change
Then place back into water bath for 2 mins
Observe again

Question 4

Colour change for reducing sugar

Answer 4

Blue to orange/brick-red

Question 5

Test for non-reducing sugar

Answer 5

Add HCl to test tube
Place in water bath for 2 mins
Remove + cool
Add sodium hydrogen carbonate until no more effervescence
Add sample
Then repeat same test for reducing sugars

Question 6

Colour change for Non-reducing sugars

Answer 6

Blue to orange/brick-red

Question 7

Test for lipids

Answer 7

Emulsion test
Add ethanol and shake thoroughly
Add distilled water and shake gently

Question 8

Colour change for lipids

Answer 8

colourless to white emulsion

Question 9

Light Microscope

Answer 9

Glass lense focuses light through the object and into the eye
resolution - 200nm
magnification - up to x2000
pros
small, cheap, shows colour, easy prep for specimen
cons
low magnification and resolution

Question 10

Electron Transmission Microscope

Answer 10

Beams of electrons through the specimens, areas that absorb more electrons appear darker
Resolution - 0.2nm
Magnification - x 1.5million
pros
high resolution, allows intricate organelles to be seen
cons
need very thin specimen, black/white images only, difficult prep, dead specimens as its viewed ina vaccum

Question 11

Scanning Electron Microscope

Answer 11

Beam of electrons is sent across the surface of the specimen and the reflected electrons are collected
Resolution - 3-10nm
Magnification - x 500,000
pros
can see specimen in 3D, no need to cut specimen, can see whole organelles
cons
same as TER