AP BIOLOGY

Detailed explanation-1: -The development of a brick-red coloured precipitate of cuprous oxide confirms the presence of reducing sugars in the analyte.

Detailed explanation-2: -When Benedict’s reagent solution and reducing sugars are heated together, the solution changes its colour to orange-red/ brick red. This colour is due to the presence of simple carbohydrates. In specific, the copper (II) ions in Benedict’s solution are reduced to Copper (I) ions, which causes the colour change.

Detailed explanation-3: -Chemical test The common disacharrides lactose and maltose are directly detected by Benedict’s reagent, because each contains a glucose with a free reducing aldehyde moiety, after isomerization.

Detailed explanation-4: -The substance to be tested is heated with Benedict’s solution; formation of a brick-red precipitate indicates presence of the aldehyde group. Since simple sugars (e.g., glucose) give a positive test, the solution is used to test for the presence of glucose in urine, a symptom of diabetes.