Which statement best describes metabolism in living organisms?

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Metabolism is the sum of all chemical reactions that sustain life, encompassing both breaking down molecules for energy (catabolism) and building new cellular components (anabolism). This broad view covers digestion, cellular respiration, photosynthesis, and the synthesis and turnover of proteins, nucleic acids, lipids, and more, as well as energy transfer and waste processing. Because metabolism includes every biochemical transformation that keeps cells functioning, it is not limited to just energy production, digestion, or replication alone. For example, DNA replication involves a series of enzymatic reactions and substrate transformations, which are part of metabolic processes, just as digestion provides the raw materials for these pathways and respiration supplies the energy. The description that best captures metabolism is therefore all chemical processes occurring in living things.