Correct Option
The correct option is Starch.
Explanation
Carbohydrates are essential biomolecules that function primarily as energy sources or structural components in living organisms. Polysaccharides, which are long chains of monosaccharides, are specialized for these roles based on their molecular structure and the specific organism in which they occur.
Option Analysis
- Starch Starch: Correct. Starch is the primary storage polysaccharide in plants. It is composed of glucose units arranged in two forms: amylose (linear) and amylopectin (branched). Plants synthesize glucose during photosynthesis and store the excess as starch in chloroplasts and amyloplasts for future energy requirements.
- Glycogen Glycogen: Incorrect. Glycogen is the primary storage polysaccharide in animals and fungi. While chemically similar to starch, it is more highly branched and is stored primarily in the liver and muscle tissues of animals.
- Cellulose Cellulose: Incorrect. Cellulose is a structural polysaccharide that forms the main component of plant cell walls. Unlike starch, which functions as an energy reserve, cellulose provides mechanical strength and rigidity to the plant. Its linear structure involves β-glycosidic linkages, making it resistant to hydrolysis by human digestive enzymes.
- Chitin Chitin: Incorrect. Chitin is a structural polysaccharide found in the exoskeletons of arthropods (such as insects and crustaceans) and the cell walls of fungi. It is a polymer of N-acetylglucosamine rather than pure glucose.
Key Takeaway
Starch serves as the energy reserve in plants, whereas Glycogen performs the same function in animals. Cellulose is strictly a structural component in plants, distinct from energy storage molecules.