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Which of the following statements about starch are correct?

1. Starch is a single pure chemical compound.
2. Starch is a mixture of two distinct polysaccharides of glucose.
3. Starch contains alpha-(1->4) glycosidic linkages connecting alpha-D-glucose units.
4. Starch contains alpha-(1->6) glycosidic linkages responsible for branching.

Correct answer: Starch is a mixture of two distinct polysaccharides of glucose.

Solution

Starch is not a single compound but a mixture of amylose and amylopectin. Both components contain alpha-1,4 glycosidic linkages; amylopectin additionally has alpha-1,6 linkages for branching. Statements B, C, and D are all correct.

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