AQA A-Level Biology Paper 1 Revision Questions and Answers

Large molecules often contain carbon. Why? they can readily form bonds with other carbon atoms. This forms a 'backbone'. Other atoms can then attach. Describe benedicts test for reducing sugars add equal volumes of the sugar sample and benedicts reagent. Heat the mixture in a water bath for 5 minutes. Brick red precipitate will form. What is a reducing sugar? a sugar that can reduce (give electrons to) another chemical. Describe the benedicts test for non reducing sugars with food sample, add an equal volume of dilute hydrochloric acid in a test tube. Place test tube in water bath for 5 mins. Add sodium hydrogencarbonate solution. Heat resulting solution with an equal volume of benedicts. Solution for 5 minutes. Turns orange/brown. What does dilute hydrochloric acid do in the benedicts test for non reducing sugars? it hydrolyses any disaccharide into monosaccharides, thus also forming reducing sugars