Biochemical tests 0.0 / 5 ? BiologyBiological moleculesASOCR Created by: Hol19Created on: 12-04-16 10:17 Bieuret test Test for proteins Positive result is when it turns from blue to lilac or purple. You add sodium hydroxide a to make sure it is alkaline you then add copper sulfate (detects the presence of peptide bonds) 1 of 4 Iodine test Test for starch add iodine in potassium iodide solution If it is a positive result you will see a colour change from yellow-brown to blue black. 2 of 4 Emulsion test Test for lipids Mix the samples with ethanol in a test tube. Pour the sample into a clean test tube with water. If lipid is present a cloudy white emulsion will indicate the presence of lipids. 3 of 4 Benedict's test This is for reducing and non reducing sugars. You heat the reducing sugar with benedicts solution If a positive result occurs it will turn into a brick red precipitate (blue to green to yellow to orange-red) If you test for non reducing sugars; Test for reducing usgars first take a sample and boil it with HCL to hydrolyse the sucrose to glucose and fructose cool the solution and use sodium hydrogencarbonate to neutralise it. Test for reducing sugars again. Should form a brick red precipitate. 4 of 4
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