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level: 1.2/1.3 Carbohydrates

Questions and Answers List

level questions: 1.2/1.3 Carbohydrates

QuestionAnswer
What is a glyosidic bond- A condensation reaction between two monosaccharides
Monosaccharides- One sugar
Disaccharides- Two sugars
Polysaccharides- Multiple sugars
What is a reducing sugar- A sugar that can donate electrons to another molecule e.g. Benedict's reagent
Test for reducing sugars- Food sample dissolved in water in test tube - Equal volume of Benedict's reagent added - Heated in water bath - If it turns orange-brown sugar is present
What is a non-reducing sugar- A sugar that cannot donate electrons to another molecule - So it can't be detected with Benedict's reagent
Test for non-reducing sugars- The non-reducing sugars must be broken down from disaccharides to monosaccharides - Add dilute hydrochloric acid - Heat in water bath - Neutralise it with sodium hydrogen carbonate (Benedict's reagent will not work in acidic conditions) - Heat it again with Benedict's reagent - If sugar is present turns orange-brown
Examples of monosaccharides- Glucose - Galactose - Fructose
Examples of disaccharides- Maltose - Lactose - Sucrose
Examples of polysaccharides- Starch - Cellulose
What monomers make MALTOSE- Glucose + glucose
What monomers make LACTOSE- Glucose + galactose
What monomers make SUCROSE- Glucose + fructose
Test for starch- Add iodine - Turns blue-black if present