Question

Real-World Scenario
Starch molecules are actually long chains of glucose molecules. When you eat food containing starches, such as potatoes, your body breaks down the starch into the glucose molecules. Your cells then use glucose to obtain energy through cellular respiration.

Based on what you learned in the lab, why does your body need to break down starch into glucose?

Starch contains more energy than glucose.

Starch molecules are too large to diffuse into cells.

Glucose molecules are larger than starch molecules.

Answer 1

Correct answer: Starch molecules are too large to diffuse into cells.

Explanation: Starch is a polysaccharide (a long chain of glucose units) and cannot pass through the cell membrane or enter metabolic pathways as a polymer. Digestive enzymes (e.g., amylase) break starch into individual glucose molecules, which are small enough to be transported into cells (via carriers like GLUT) and used directly in glycolysis and cellular respiration. The other two choices are incorrect: glucose is smaller than starch, and the need to break starch down is about size/transport and enzyme specificity, not that starch inherently contains more energy.