Question

Aerobic respiration is ultimately the reaction of glucose with oxygen to generate carbon dioxide, water, and energy. However, in a cell this process involves the transfer of electrons from glucose to carriers such as NAD over a lengthy series of steps. Why don't cells employ the direct reaction of glucose with oxygen to generate energy?

Answer 1

Answer:

Glucose is a very  high energy rich stable compound.Therefore to extract the energy it contains it must first be broken down in a step wise reactions called Glycolysis to generate ATPs needed  in subsequent  steps.

If glucose molecules reacted directly with oxygen(burnt in oxygen). This is an example of  combustion reaction, which  involves the transfer of electrons between  glucose and oxygen atoms  through pathways in which the   energy produced  can not be harness by the cells.it  is  therefore not physiologically compatible with normal  cellular reactions of life.

Answer 2

Answer:

Cells don't employ the direct reaction of glucose with oxygen to generate energy because the direct transfer of electrons from glucose to oxygen occurs via a combustion reaction that is incompatible with life.

Explanation:

Aerobic respiration is a process by which chemical energy is released in cells during the breakdown of food e.g glucose.

Cells don't employ the direct reaction of glucose with oxygen to generate energy because the direct transfer of electrons from glucose to oxygen occurs via a combustion reaction that is incompatible with life.

NAD is used to temporarily store high energy electrons harvested from glucose molecules in a series of gradual steps in the cytoplasm.