Question

# One mole of stachyose on hydrolysis yields:A.1 mole of glucose + 1 mole of fructose + 2 mole of galactoseB.2 mole of glucose + 1 mole of fructose + 1 mole of galactoseC.1 mole of glucose + 2 mole of fructose + 1 mole of galactoseD.2 mole of glucose + 2 mole of fructose

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A tetrasaccharide is a saccharide or carbohydrate which upon hydrolysis gives four molecules of the same monosaccharide or different monosaccharides. The general formula of tetrasaccharides is ${{\text{C}}_{{\text{24}}}}{{\text{H}}_{{\text{42}}}}{{\text{O}}_{{\text{21}}}}$ . The monosaccharides are the simplest carbohydrates which cannot be hydrolyzed further to smaller molecules. Their general formula is ${\left( {{\text{C}}{{\text{H}}_{\text{2}}}{\text{O}}} \right)_{\text{n}}}$ where n is equal to 3-7.

Stachyose is an example of a tetrasaccharide. It gives four molecules of different monosaccharides on complete hydrolysis. These four molecules are one molecule of glucose, one molecule of fructose and two molecules of galactose. Thus, stachyose consists of two ${\text{alpha }}$ - D - galactose units, one ${\text{alpha }}$ - D - glucose unit and one ${\text{beta }}$ - D - fructose unit. Thus, option A is the correct answer. The structure of stachyose is shown below.