AS BIOLOGY P-33

[kelly sheers]

Can some one please share the food test procedures and will we have a graticule scale and all that?

i rely hope this is not too messy
biuret test : add an equal amount of NaOH to a solution of the food, mix carefully.
add a few drops of 1% CuSO4, do not shake the mixture.
a PURPLE/MAUVE COLOR is a positive result: protein is present.

iodine test:
1. If the food to be tested is liquid, go to 2. If the food to be tested is solid, make an extract. Grind crush or chop a
small amount and put into a test tube to a depth of about 2cm. Add a similar amount of distilled water and stir with
a glass rod. Allow to stand for a few minutes.
2. Draw up some of the clear liquid into a pipette and then either transfer it into another test tube or put drops onto
a white tile.
3. Add on drop of (brown) iodine solution on the tile and look for a color change. A blue-black color indicates
the presence of starch.

benedicts' test :for reducing sugar

. Add
about
5cm3of
the
reagent
to
a
small
amount
of
sample
in
a
test
tube.


.Stand
the
test
tube
in
boiling
water
for
a
few
minutes.



A
colour
change
through
green
to
yellow,
brown
and
finally
to
red
indicates
the
presence
of
reducing
sugar

for non reducing sugar :
01.If the sample isn't already in liquid form grind it up in water.
2. Add 2cm3(cubed) of the food sample to a test tube with 2cm of benedict's reagent
3. gently) boil in a water bath for 5 mins
4. If a NON-REDUCING sugar is present then the solution will remains BLUE
5. In this case another 2cm3 of the food sample to 2cm3 of (dilute) hydrochloric acid in a test tube(as the hydrochloric acid hydrolyzes the disaccharide into its monomer constituents .i.e. sucrose --> glucose + fructose)
6. (Slowly) add sodium hydrogencarbonate to the test tube(to neutralise the hydrochloric acid as Benedict's reagent can't work in acidic conditions)
7. Now re-test the solution by heating it with the 2cm3 of Benedict's reagent for 5 mins, this time the solution should turn from blue to orange-brown/brick red because reducing sugars are present(.i.e. glucose and fructose)due to the hydrolysis of the disaccharide (sucrose)

 

[Ahmad Zaeem]

diagram for monocot stem

these images may come in handy .......thanks

 

[aleezay]

Guys the test for non- reducing sugar is, first taking the non-red sugar with benedicts and heating it in water bath for a specified time and then adding HCL and then neautralising it with sodium bicarbonate.. ? am I right

you add the acid + neutralise it BEFORE carrying Benedict's test

 

[a level freak]

Hello. Can you guys help me distinguish between LPP and HPP diagram? I couldnt get the part where they say do not draw individual cell in LPP.
what is full form of lpp and hpp

 

[stareaj]

another version

When drawing plan diGram for this will we draw the fibres too?
Can sombody pleass drW
a plan diagram for monocot stem

 

[aleezay]

but what is lpp and hpp (full form)

Low and high power plan diagrams

 

[Taha.Sajid]

Guys all we need now are the plan diagrams of Dicot stem and root.Someone please post them here.It would be much appreciated.

 

[siraj acharya]

can someone make the question a bit more clear ?

 

[Alool]

green -- means traces present . yellow --- low amounts ... orange --- moderate amounts ....brick red --- high amounts

yes i know this i mean when they ask us record the time for the first colour change.. so when it turns green ill record the time?

 

[aleezay]

Somebody posted this in some other thread a few months ago..dont know who.. this might help clear many confusions regarding food tests and microscopy

 

[Ahmad Zaeem]

Guys all we need now are the plan diagrams of Dicot stem and root.Someone please post them here.It would be much appreciated.

they are posted above dude .....Surf previous 1 or 2 pages you will find real good diagrams!!!

 

[aleezay]

they are posted above dude .....Surf previous 1 or 2 pages you will find real good diagrams!!!

those are for monocod plants

 

[kelly sheers]

these images may come in handy .......thanks

 

[a level freak]

test upon sucrose, glucose, starch and fungal amylase.
How do we test the sucrose ,glucose,starch and fungal amylase

 

[falcon678]

How do you know this is true?? Although our bio teacher also had us practice food tests!

well ummm my info on chem n phy were correct?

 

[kelly sheers]

When drawing plan diGram for this will we draw the fibres too?
Can sombody pleass drW
a plan diagram for monocot stem

u mean the fibre cap? the sclerenchyma? dat depends on the question

 

[raamish]

guys in cell division if a cell is in prophase should we draw the chromatin threads in our low power diagram and nuclelous if we see them

 

[Taha.Sajid]

If you are reffering to these then i must tell you these are not the "planned diagrams" .These are original images of specimens.

 

[MaxStudentALevel]

well ummm my info on chem n phy were correct?

Really?? Like 100%??

 

[a level freak]

how to test upon sucrose and fungal amylase