The energy difference between the reactant glucose and oxygen molecules and the product water and carbon dioxide is 686 kilocalories, yet the 36 ATP molecules produced are only storing 263 kilocalories in their outermost phosphate bond. The rest of the energy
A) was added to the ADP fragment of the ATP molecule.
B) provided the energy for life.
C) powered the electron transport chain.
D) was lost as heat.
E) went nowhere, but was destroyed.

Question

Quizplus · Accepted Answer

The rest of the energy not stored in ATP molecules is lost as heat during cellular respiration. This is a consequence of the second law of thermodynamics, which states that energy transformations are not 100% efficient and some energy is always lost as heat.

The Energy Difference Between the Reactant Glucose and Oxygen Molecules