Question 12

Aerobic respiration occurs in the presence of oxygen.

Aerobic respiration requires oxygen to effectively convert glucose into energy. This process involves the use of oxygen to fully oxidize glucose, resulting in the production of carbon dioxide, water, and energy.

A) Carbon Dioxide

Carbon dioxide is a byproduct of aerobic respiration, not a necessary molecule for the process to occur. While it is generated during the breakdown of glucose, it does not facilitate the respiration itself.

B) Water

Water is also a byproduct of aerobic respiration, produced alongside carbon dioxide during the energy conversion process. However, it is not a necessary molecule; instead, it is a result of the chemical reactions that take place when oxygen is utilized.

C) Glucose

Glucose is indeed a vital substrate for aerobic respiration, providing the energy source that is metabolized. However, without the presence of oxygen, aerobic respiration cannot occur; it transitions to anaerobic respiration instead.

D) Oxygen

Oxygen is the essential molecule for aerobic respiration, allowing cells to oxidize glucose completely. It enables the efficient production of energy, which is critical for cellular functions.

Conclusion

Oxygen is unequivocally the necessary molecule for aerobic respiration, as it is required to fully oxidize glucose. The other options, while related to the process, do not serve as the primary requirement for aerobic respiration to take place. Thus, option D stands out as the definitive correct answer.