Summary Edexcel IAS Level Biology Unit 3 Complete Notes (Lab Practicals)

, PRACTICALS

Benedicts Test
Detects the
presence of reducing sugars
·




Benedict's blue that (11)
reagent is a solution contains
Copper Sulphate
·




-copper (I) Oxide is insoluble in water ,
so it forms a
precipitate
-

Procedure :
in excess
&
>
Add Benedict's reagent to in test tube
a
sample solution a


>
Heat the test tube in a water bath for a few mins


reducing
·



In colourised
presence precipitate
a
of a
sugar ,




The colour the
precipitate depends on the concentration of
-




of

reducing sugars
Blue reel
>
, green ,
yellow , orange ,



low Conc >
high conc




Testing non-reducing sugar
-

Procedure
>
Add Hel to the
sample
Benedict's
Carry the rest test
-
out of




Biuret test

Test
for protein
·




Biuret blue
reagent contains an alkali
Copper (1) sulfate and has colour
·
a



Reaets the bonds
with
peptide that holds the amino acids
together ,
-




which make
up proteins
·
Procedure

Add
drops birret
> the
a
few of reagent to
sample
> A colour
change is observed from blue to lica/purple when
proteins
are
present
·
Hold the test tube to white tile to better observe the colour
change