Semmelweis Medicine Biology Entrance Practice Exam

During the chemiosmosis stage of cellular respiration, a significant portion of ATP is produced through oxidative phosphorylation, which occurs in the mitochondria. This process relies on the electron transport chain and the establishment of a proton gradient across the inner mitochondrial membrane. As protons flow back into the mitochondrial matrix through ATP synthase, this movement drives the conversion of ADP and inorganic phosphate into ATP.

Approximately 34% of the total ATP generated during cellular respiration comes from this stage of chemiosmosis. This high yield results from the efficiency of the electron transport chain and the energy harnessed from the proton gradient. Thus, the correct percentage of ATP produced during the chemiosmosis stage aligns with the choice indicating 34%.