What best defines metabolism?

Metabolism is best defined as a process by which cells are nourished. This encompasses the biochemical processes that occur within living organisms to maintain life, including the conversion of food into energy and the building blocks necessary for growth and repair. Metabolism involves both anabolism, which is the building-up of molecules, and catabolism, the breaking down of molecules to release energy. This means that metabolism is crucial for providing the nutrients and energy that cells require to function properly and sustain various physiological processes.

In contrast, waste elimination refers to processes that remove byproducts from the body, which is not a direct part of metabolism. Cell division pertains to how cells replicate, and while metabolism is crucial for supporting the energy needs of growing cells, it doesn’t define the act of division itself. Lastly, protein synthesis, while an important aspect of metabolism involving anabolism, does not encompass the entire definition of metabolism, which also includes various other processes beyond just the creation of proteins. Therefore, the option focusing on how cells are nourished accurately captures the essence of metabolism as a whole.