Final answer:
The most stable form of oxidized carbon is CO2, which cycles back into the organic portion of the carbon cycle through photosynthesis. Hence, the correct answer is (A) CO2, photosynthesis. Cellular respiration and photosynthesis create a vital biological cycle powered by solar energy.
Step-by-step explanation:
Oxidation is a favorable process in an aerobic environment, critical for cells to derive energy from the oxidation of macromolecules. Once carbon has been oxidized to CO2, its most stable form, it can only cycle back into the organic portion of the carbon cycle through photosynthesis. Thus, the correct answer to the question is (A) CO2, photosynthesis.
Cellular Respiration and Photosynthesis
In cellular respiration, carbon atoms from carbohydrates are oxidized, losing electrons and hydrogens to form carbon dioxide (CO2). Oxygen is reduced, gaining electrons and hydrogen ions to form water (H2O). This critical reaction is reversible; photosynthesis allows plants to absorb light energy and reduce carbon dioxide back into carbohydrates, such as glucose, using the energy derived from sunlight.
Cyclical Harmony of Biological Processes
These two processes, photosynthesis and aerobic cellular respiration, function in a cyclical harmony, allowing life to exist thanks to the energy that originates from the sun. Aerobic respiration and photosynthesis can be essentially viewed as opposite processes.