Which of the following statements about starch and cellulose is TRUE?

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BlackTom AI · Accepted Answer

Question: Which of the following statements about starch and cellulose is TRUE?

Option 1: 'animals can store glucose as starch and cellulose' This is incorrect because animals store glucose as glycogen, not starch. Starch is the storage polysaccharide used by plants, while cellulose is a structural polysaccharide in plant cell walls. Animals do not have the enzymes to hydrolyze cellulose for energy in humans, though some herbivores can digest cellulose with gut microbes.

Option 2: 'both are dietary fibres' This is not accurate. Dietary fiber typically refers to non-digestible carbohydrate components of plant foods. While cellulose is indeed a dietary fiber for many people, starch is digestible and serves as a major energy source, so labeling both as dietary fibres is misleading.

Option 3: 'starch is a polysaccharide, but cellulose is not' This is false. Both starch and cellulose are polysaccharides composed of glucose units. Starch is mainly α-1,4 and branched α-1,6 linkages (amylose and amylopectin), whereas cellulose consists of β-1,4 linkages, yielding a rigid, fibrous structure that humans cannot digest without specific enzymes.

Option 4: 'only starch is an energy molecule for humans' This aligns with physiological reality. Starch is digestible by humans to glucose, providing a major energy source. In contrast, cellulose resists digestion due to its β-1,4 glycosidic bonds and serves primarily as dietary fiber, aiding digestion but not providing usable energy for humans.

Which of the following statements about starch and cellulose is TRUE?

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