Which statement best describes coupled reactions?

Coupled reactions refer to the process where an exergonic reaction, which releases energy, is used to drive an endergonic reaction, which requires energy input. This relationship is crucial in biological systems, enabling organisms to perform necessary cellular functions even when those functions are energetically unfavorable by coupling them with reactions that release energy.

For example, in cellular respiration, the breakdown of glucose (an exergonic reaction) releases energy that is subsequently used to drive the synthesis of ATP (an endergonic reaction). This coupling allows cells to efficiently manage energy flow, ensuring that the energy released from catabolic processes can be harnessed to fuel anabolic processes.

The other statements do not accurately reflect the nature of coupled reactions. While both reactions may be energetically favorable in certain contexts, coupled reactions specifically involve the action of a driving exergonic reaction facilitating an energy-demanding endergonic reaction. Independent reactions do not interact with each other in this way, thus lacking the unique interdependent energy transfer characteristic of coupled reactions.