biochemical tests 0.0 / 5 ? BiologyBiological molecules, organic chemistry and biochemistryASOCR Created by: Aimee GernonCreated on: 29-05-14 12:53 TESTING FOR REDUCING SUGAR Reducng sugars include all monosaccharides and some disaccharides USE BENEDICTS TEST add benedicts solution to sample and heat (do not boil) if a reducing sugar is present a coloured precipitate is formed colour changes frrom BLUE -> GREEN -> YELLOW -> ORANGE-> BRICK RED 1 of 5 TESTING FOR NON-REDUCING SUGAR to test non-reducing sugars they must first be broken down into monosaccharides PROCEDURE: boil the sugar e.g. sucrose with dilute hydrochloric acid neutralise the solution with sodium hydrogencarbonate use the BENEDICTS TEST to work out whether it is reducing or non-reducing 2 of 5 TESTING FOR STARCH USE IODINE TEST add drops of iodine dissolved in potassium iodide solution if starch is present the sample changes from ORANGE/BROWN -> BLUE/BLACK if starch is not present there will be no colour change 3 of 5 TESTING FOR PROTEINS USE BIURET TEST involves 2 stages: 1... the soultion needs to be alkaline so add drops of sodium hydroxide solution 2... Add some copper(II) sulfate solution if a protein is preset a PURPLE layer is formed at the surface if there is no protein the solution will remain BLUE 4 of 5 TESTING FOR LIPIDS USE EMULSION TEST add ETHANOL to substance and shake for 1 minute pour solution into WATER if lipid is present souliton will turn MILKY no lipid solution will stay clear 5 of 5
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