Which statement differentiates starch from cellulose?

• A. Starch uses alpha glucose resulting in a helical molecule.
• B. Starch uses beta glucose resulting in linear strands.
• C. Cellulose uses alpha glucose resulting in helical strands.
• D. Cellulose uses beta glucose resulting in linear strands.

Answer: (A)

Starch and cellulose differ in the type of glycosidic bonds between glucose units, and that dictates the overall shape of the polymer. Starch is built from alpha-linked glucose units (primarily alpha-1,4 bonds in the main chain, with some alpha-1,6 branches in amylopectin). The alpha linkage causes the chain to adopt a helical shape, which is compact and suited for storing glucose. Cellulose, by contrast, is made of beta-linked glucose units (beta-1,4 bonds). The beta linkage flips every other glucose, producing straight, unbranched chains that can align and form strong hydrogen-bonded fibers.

That’s why the statement asserting starch uses alpha glucose resulting in a helical molecule is the distinguishing one: it captures both the sugar’s configuration and the resulting structural form, which sets starch apart from cellulose. The other options misstate the type of glucose or the resulting structure, so they don’t correctly differentiate the two polymers.