Glucose molecules provide the chemical energy cells use to carry on life processes. Some energy is always lost when cells break down the glucose molecules. Which statement explains how energy is lost in this process?

A) Some energy is changed back to glucose.

B) Some energy is converted into mass.

C) Some energy is converted into heat.

D) Some energy is changed into ADP.

C) Some energy is converted into heat.

Explanation:

Oxidation of glucose occurs by the process of cellular respiration. Cellular respiration temporarily stores the chemical energy released during step by step breakdown of glucose in form of reducing power NADH and FADH2. Oxidation of NADH and FADH2 during the final stage of cellular respiration drives the synthesis of a large number of ATPs.

However, cellular respiration follows the second law of thermodynamics and is not a 100% efficient process of energy transformation. Out of a total of 686 kcal energy stored in one glucose molecule, around 39% is stored in 38 ATP molecules and rest is lost as heat.

The correct answer is C) Some energy is converted into heat.

Explanation:

Cell can not use all the energy released by the oxidation of glucose molecule because some of the energy is dissipated as heat energy in the environment and the left energy is used by the cell to carry out metabolic processes important for cell living.

Oxidation is the process in which electrons move from one molecule to another and during each oxidation step some energy is lost as heat and the product has less energy than the reactant.

Therefore during the oxidation of glucose some energy is lost as heat and the rest of the energy is stored in the form of ATP molecule for further use by cells. Glucose after fully oxidation released as the waste product in the form of CO₂ by the cell.

So the right answer is C) Some energy is converted into heat.