Food tests Biology Edexcel GCSE Questions Fully Solved Graded A+.

Test for sugar - correct answer Benedict's test How to do sugar test - correct answer Add Benedict's reagent to sample, heat in water bath to 75 degrees Results for sugar test - correct answer Positive = coloured precipitate brick red. Negative = stay blue Test for starch - correct answer Iodine solution How to do starch test - correct answer Add iodine to sample and view results Results for starch test - correct answer Positive = blue-black. Negative = browny-orange Test for lipids - correct answer Emulsion test How to do emulsion test - correct answer Shake sample with ethanol until it dissolves then pour into water. Results for emulsion test - correct answer Positive = lipids will precipitate out of the solution and show as a milky emulsion. Negative = nothing Test for protein - correct answer Biuret test How to do buiret test - correct answer Ass a few drops of potassium hydroxide solution to make the solution alkaline. Add some copper sulphate solution. Results for biuret test - correct answer Negative = stay blue Positive = turn purple