QUESTIONS Use these questions to help you structure and write your lab report an
ID: 145639 • Letter: Q
Question
QUESTIONS Use these questions to help you structure and write your lab report and also study for your exam. 1. Explain the limitations of Benedict's test in determining whether or not sugar is present in a certain food product. Why do all monosaccharides, but only some disaccharides, react with Benedict's reagent? 2. What did you learn about the specificity of the biuret reagent? Ninhydrin reacts with a mixture of amino acids and turns purple. Could proline be one of the amino acids? 3. How could you find out if the mixture contained proline?Explanation / Answer
Benedict test is given by mono saccharide likes glucose,fructose,and maltos and some reducing disaccharide those compound which have aldehyde, alpha hydoxy ketone and hemiacetal group gives bendict test.
Bendict reagent is mixture of sodium carbonate, sodium citrate,and coper sulfate.any substance that reduce the cupric ion to cupric ion in alkaline medium gives Benedct test.
A positive test is shown by colour change from blue to brick red precipitate.
All monosaccharide and some disaccharide like lactose maltose gives benedicts test because each contain glucose with free reducing aldehyde group.some disaccharide like sucrose have two sugar glucose and fructose both sugar are joned by glycosidic bond in such a way as to prevent the glucose isomerizing to aldehyde or the fructose to alpha hydroxy ketone..thus sucrose is non reducing sugar which does not give Benedict test.