Qualification > Sciences

help plzz in bio practicals

(1/1)

Mary_2nd:
i wna kno da exact methods 4 testing 4
1)reducing sugars
2)proteins
3)starch
don't jst write da indicator n da colour chng i wnt all da stepz plz
like boil da water n all
thnxx in advance:)

Muho:
Okay here are the stuff:

Reducing sugars (glucose)
take the suspected sample and add Benedict's solution into it, in a test tube or something, or in a beaker. Then heat the water gently with a Bb. If this happens:
Blue --> Blue
Then there is no reducing sugar present
If this happens:
Blue --> Brick red
Then there is reducing sugar present.

Starch
for starch you add iodine solution to the suspected sample
Brown --> Brown
This is a negative result
Brown --> Blue/black
This is a positive result

Protein
Protein is easy too =p all you do is use the biuret. If the sample is a solid, crush it, add it into a test tube or a beaker or something, add water to it, [if it's a liquid you're going to test then don't do what i mentioned previously] then add biuret solution into it. i don't know what's the colour for biuret... but it changes to blue/purple.

hope it helped. =D

jkiam11:
More often the examiners will give you sodium hydroxide and copper sulphate instead of biuret soln.
So you would simply follow what Muho said then add sodium hydroxide and copper sulphate instead of biuret soln. Colour change is blue to purple.

asus:
http://www.purchon.com/biology/food.htm

There u go.. ;)

Navigation

[0] Message Index