Chemiosmotic Hypothesis & ATP Synthesis — NEET Biology
📚 Practice ConceptYou have already studied about the mechanism of membrane-linked ATP synthesis as explained by chemiosmotic hypothesis in the earlier chapter. As mentioned earlier, the energy released during the electron
Which of the above statements are correct regarding the step-wise release of energy in cellular respiration? S1: The complete oxidation of glucose in cellular respiration occurs through a single explosive reaction, releasing all energy at once to maximize heat generation. S2: Energy released during the series of step-wise reactions in respiration is directly usable for metabolic activities without conversion into ATP. S3: The strategy of multi-step oxidation of glucose ensures that energy released can be coupled to ATP synthesis, thereby capturing it gradually rather than losing it as excessive heat. S4: Molecules like NADH + H+ and FADH2 serve as temporary energy carriers, storing energy from earlier catabolic steps to be utilized later for ATP production through oxidative phosphorylation. S5: The process of oxidative phosphorylation in respiration involves light energy for creating a proton gradient, similar to photophosphorylation in photosynthesis.
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Correct answer: B — S3 and S4 only
The core concept tested is the significance of the step-wise energy release during respiration and its coupling to ATP synthesis. S1 is NOT correct. Respiration involves a series of slow, step-wise reactions, not a single explosive one, to prevent excessive heat loss and efficiently trap energy. S2 is NOT correct. The energy released from respiratory substrates is not used directly; instead, it is first trapped in the form of ATP, which then acts as the energy currency for various cellular processes. S3 is correct. The multi-step oxidation of glucose is a cellular strategy to gradually release energy in manageable amounts, allowing it to be coupled with ATP synthesis and thus minimizing its loss as unusable heat. S4 is correct. NADH + H+ and FADH2 are crucial intermediate energy carriers. They are reduced during glycolysis and the Krebs' cycle, storing energy which is later released through their oxidation in the Electron Transport System to drive ATP synthesis via oxidative phosphorylation. S5 is NOT correct. Oxidative phosphorylation utilizes the energy of oxidation-reduction for creating a proton gradient, unlike photophosphorylation which uses light energy. NCERT explicitly differentiates between these two processes regarding their energy source. Therefore, statements S3 and S4 are correct. This question assesses the understanding of why respiration is a multi-step process and how energy is conserved and utilized.
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.