Final answer:
Glucose is the molecule that is broken down in the process of cellular respiration to produce ATP, which is used as cellular energy.
Step-by-step explanation:
According to the model of cellular respiration, the molecule that is broken down and converted to usable cellular energy is glucose (c). Through the process of cellular respiration, cells convert the chemical energy in glucose into ATP (adenosine triphosphate), which is the primary energy-carrying molecule used by cells. While breaking the chemical bonds in glucose, cells release stored energy and make ATP they need.
Polymers from the food we eat are broken down into their monomer building blocks, such as the monosaccharide glucose, through catabolic reactions. Glucose is then oxidized in cellular respiration to produce ATP, while by-products such as carbon dioxide and water are also created. The ATP produced through this process is vital for cellular functions and the energy demands of an organism.