OCR Biology F212 Revision [3rd June 2013] (Now Closed)

The following tests are part of the specification for biological molecules, could someone please bullet point how to do each one as you would get marks for on the mark scheme. Thank you!
(r) describe how to carry out chemical tests to identify the presence of the following molecules: protein (biuret test), reducing and non-reducing sugars (Benedict’s test), starch (iodine solution) and lipids (emulsion test);
(s) describe how the concentration of glucose in a solution may be determined using colorimetry (HSW3).

Explain an experiment using the water displacement method (Water bath, delivery tube, test tube filled with water upside down in the water bath and a conical flask where the experiment is taking place with the cork and delivery tube attached at the top)
An example is the breakdown of H₂O₂ using the enzyme catalase to form H₂O and O₂
The release of O₂ can be recorded in the volume of gas collected from the delivery tube into the water bath and the rate of O₂ collection is effectively the volume of Oxygen collected divided by the time taken
Record these results, make a graph etc
Change each variable (pH etc) keeping other variables constant
Record the effect of these variables on rate of reaction (enzyme activity)

Hope that helped

During Semi-conservative replication does the DNA polymerase help break the hydrogen bonds between the bases apart? Or does it help during Proteinsynthesis? Or is it used for both?

Isn't Fe2+ in-organic tho ?

During Semi-conservative replication, is 'DNA unzips' the same as saying The hydrogen bonds between the bases are broken apart?

1) PROTEIN- add a fews drops of Biuret solution (which contains NaOH and CuSO4) in cool sample.
Chemicals react with the peptide bonds, and if protein is present, colour changes from pale blue to lilac.

2) REDUCING SUGAR- All monosacchrides and some disaccharides (e.g. maltose) are reducing sugar.
You place a few drops of Benedicts Solution to the sample and you heat it in a water bath to 80 degrees.
If reducing sugar is present, colour changes from blue to a brick red precipitate (of CU2+)

3) NON- REDUCING SUGAR- Most disaccharides are reducing sugars (e.g. sucrose and lactose)
First of all, you ensure that no-reducing sugar is present in the sample (carry out a negative benedicts test).
Then you boil the sample with HCL (this hydrolyses the non-reducing sugar, so that the glycosidic bond between the disaccharide molecule breaks apart, to form reducing sugars)
Then you cool the solution and neutralise with Na2CO3 (as Benedicts test doesn't work in an acidic environment)
Then you add Benedicts solution the second time round, and if the non-reducing sugar was present in the original sample, colour changes from blue to an orange/red precipitate.

4) LIPID
Mix sample with ethanol (this dissolves any lipid present)
Pour the resulting solution into another clean test tube containing water
If lipid is present, a cloudy white emulsion will form.

5) STARCH
Add a solution of iodine ( in potassium iodide) to sample.
If starch is present, colour changes from yellow/brown- blue/black

Did the january 2013 paper..just got a D..feeling very confident for the exam..not
similarities and difference between Starch and cellulose?

Guys whats a vector?

Guys whats a vector?

Describe the actions of t lymphocytes in the immune response (8)

T killer : Engulfs and destroys infected cells

can someone outline the lock and key theory for me in specific marks?