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Questions and Answers
Which test can differentiate between monosaccharides and disaccharides based on the speed of the reaction?
Which test can differentiate between monosaccharides and disaccharides based on the speed of the reaction?
What is indicated by the formation of a silver mirror or a reddish-brown precipitate in a test?
What is indicated by the formation of a silver mirror or a reddish-brown precipitate in a test?
Which test shows a positive result by changing color to green, yellow, orange, or brick-red?
Which test shows a positive result by changing color to green, yellow, orange, or brick-red?
Which test is used to detect the presence of all types of carbohydrates by observing the formation of a violet ring?
Which test is used to detect the presence of all types of carbohydrates by observing the formation of a violet ring?
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What distinguishes ketoses from aldoses in the Seliwanoff's Test?
What distinguishes ketoses from aldoses in the Seliwanoff's Test?
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Which crystals formed are described as a 'bundle of hay'?
Which crystals formed are described as a 'bundle of hay'?
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What does a positive result in the Iodine Test indicate?
What does a positive result in the Iodine Test indicate?
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Which test helps in identifying reducing sugars by observing crystalline derivatives under a microscope?
Which test helps in identifying reducing sugars by observing crystalline derivatives under a microscope?
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Study Notes
Carbohydrate Tests
- Benedict's Test detects reducing sugars, indicated by a color change from blue to green, yellow, orange, or brick-red, depending on the concentration of reducing sugars.
Detection of Monosaccharides and Disaccharides
- Barfoed's Test differentiates between monosaccharides and disaccharides, with monosaccharides giving a positive result (reddish-brown precipitate) faster than disaccharides.
Aldoses and Ketoses
- Seliwanoff's Test differentiates between aldoses and ketoses, with positive results for ketoses showing a rapid formation of a cherry-red color.
Starch Detection
- Iodine Test detects the presence of starch, indicated by a change from yellow-brown to blue-black in the presence of starch.
Reducing Sugars
- Tollen's Test identifies reducing sugars, indicated by the formation of a silver mirror or a reddish-brown precipitate.
Carbohydrate Detection
- Molisch Test detects the presence of all types of carbohydrates, indicated by the formation of a violet ring at the interface of the two liquids.
Osazone Formation
- Osazone Formation (Phenylhydrazine Test) identifies reducing sugars, observed by the formation of osazones (crystalline derivatives) under a microscope.
- Glucosazone crystals, formed by glucose, are often described as a "bundle of hay".
- Lactosazone crystals, formed by lactose, are described as a "powder puff".
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Description
This quiz covers the principles and results of three common laboratory tests for carbohydrates: Benedict's test for reducing sugars, Barfoed's test for differentiating between monosaccharides and disaccharides, and Seliwanoff's test for distinguishing between aldoses and ketoses.
