MCQ (Previous Year Questions) - Biomolecules (Level 2)

Solution: Aldehydes and α- hydroxy ketones give positive Tollen’s test. Glucose has an aldehydic group and fructose is an α hydroxy ketone.

Solution: The two forms of D glucopyranose are called ANOMERS since they differ at configuration at the first carbon.

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Solution: You can identify a sugar by looking for the anomeric carbon. (The anomeric C is the first stereocenter of the molecule.) If that stereocenter has an OH group coming off of it then it is a reducing sugar. Hence (B) is correct. As for (C) alpha bonds are formed when the OH on the carbon-1 is below the glucose ring. While beta bonds are formed when the OH is above the plane. Hence the stereochemistry of the two compounds show that Y has a Beta linkage. Hope it helps.

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Solution: It is bita glucose or bita pyranose so an aldohexose.