Respiration In Plants

The role of the electron transport system is set out in NCERT Class 11, Chapter 14 (Respiration in Plants). Electrons carried by NADH and FADH2 are passed through a series of carriers embedded in the inner mitochondrial membrane, releasing energy used to pump protons and drive ATP synthesis. At the end of this chain, the electrons must be handed to a terminal acceptor so that the carriers can be regenerated and the chain can keep running. In aerobic respiration, molecular oxygen serves as this final electron acceptor; it combines with the electrons and protons to form water, which is why oxygen is indispensable for aerobic respiration. Carbon dioxide is a product released earlier during decarboxylation steps, not an electron acceptor. NAD plus is an electron carrier that becomes reduced to NADH and donates electrons to the chain rather than accepting them at the terminus. Pyruvate is a substrate processed before the electron transport stage, not its final acceptor. A logical consistency check supports the answer: because water forms only when oxygen accepts the spent electrons, the absence of oxygen halts the chain, confirming oxygen as the terminal acceptor.