Final answer:
The polymerization of amino acids into polypeptides must be coupled to an energetically favorable reaction, like ATP hydrolysis, to occur since it's an energy-requiring anabolic process.
Step-by-step explanation:
The process that must be coupled to an energetically favorable reaction in order to occur is polymerization of amino acids into polypeptides. This is an anabolic reaction where amino acids are covalently linked to form polypeptide chains, a process that requires energy input. In cells, energy is usually provided by the hydrolysis of ATP, which is an energetically favorable reaction. The linkage of amino acids involves dehydration synthesis, in which a water molecule is released and a peptide bond is formed, driven by the energy from ATP hydrolysis.
On the other hand, the conversion of protein into amino acids, conversion of glucose to carbon dioxide and water, and the hydrolysis of ATP are all processes that release energy and are known to be catabolic and typically exergonic. Hence, these processes do not require coupling to energetically favorable reactions to occur as they, by themselves, release energy.