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The law of conservation of mass states that in any chemical reaction, the mass of the reactants is equal to the mass of the products. Therefore, the correct statement about the process of cellular respiration that demonstrates the law of conservation of mass is:
"The total mass of glucose and oxygen is equal to the total mass of carbon dioxide and water."
During cellular respiration, glucose and oxygen are used as reactants to produce carbon dioxide, water, and energy (in the form of ATP). The reactants (glucose and oxygen) have a certain mass, and the products (carbon dioxide, water, and ATP) also have a certain mass. According to the law of conservation of mass, the total mass of the reactants (glucose and oxygen) must be equal to the total mass of the products (carbon dioxide, water, and ATP). Therefore, the statement that "The total mass of glucose and oxygen is equal to the total mass of carbon dioxide and water" correctly demonstrates the law of conservation of mass in the process of cellular respiration.