tests

Question 1

what is the test for proteins

Answer 1

biuret test confirms presence of peptide bond

Question 1

method for testing for protein

Answer 1

1.add equal vol of sodium hydroxide to a sample at room temp
2.add drops of dilute copper iii sulphate solution and stir to mix

Question 2

positive result of protein test

Answer 2

blue to purple

Question 3

negative result of protein test

Answer 3

solution remains blue

Question 4

what is the method for lipids

Answer 4

1.dissolve solid samples in ethanol
2.add an equal volume of ice water and shake

Question 5

positive result of lipid test

Answer 5

milky white emulsion

Question 6

test for reducing sugars

Answer 6

1. add an equal vol of Benedict’s solution
   2.heat the mixture In an electric water bath at 100 for 5 mins

Question 7

positive result of reducing sugars

Answer 7

blue to brick red precipitate

Question 8

test for non reducing sugars

Answer 8

1. bendectics solution remains blue
   2.hydrolyse non reducing sugars into their monomers by adding 1cm3 of HCL
   heat in boiling water bath for 5 mins
   3.neutralise mixture buying sodium carbonate solution
   4.proceed with Benedict’s test as usual

Question 9

test for starch

Answer 9

1.add iodine solution

Question 10

positive result of starch test

Answer 10

orange to blue/ black

Question 11

how can the concentration of a solution be measured quantitatively

Answer 11

colorimetry or biosensors

Question 12

what are rf values and how are they calculated

Answer 12

ratios that allow comparison of how far molecules have moved in chromatography
calculated by distance between spot and origin / distance between solvent front and origin