Chemiosmotic ATP Synthesis in Chloroplasts — NEET Biology
✅ Asked in NEET 2024Synthesis of ATP linked to development of a proton gradient across a membrane is: (NEET 2024)
Synthesis of ATP linked to development of a proton gradient across a membrane is: (NEET 2024)
Answer & NCERT explanation
Correct answer: C — Chemiosmotic hypothesis
Chemiosmotic hypothesis explains ATP synthesis linked to proton gradient development across membranes. Proposed by Peter Mitchell and mentioned in NCERT, it describes how proton pumping creates electrochemical gradient that drives ATP synthase. Other hypotheses: mass flow explains phloem transport, wobble explains codon-anticodon pairing, rivet popper is ecological concept.
Read more NCERT concept on the PYQ
Let us now try and understand how actually ATP is synthesised in the chloroplast. The chemiosmotic hypothesis has been put forward to explain the mechanism. Like in respiration, in photosynthesis too, ATP synthesis is linked to development of a proton gradient across a membrane. This time these are the membranes of thylakoid. There is one difference though, here the proton accumulation is towards the inside of the membrane, i.e., in the lumen. In respiration, protons accumulate in the intermembrane space of the mitochondria when electrons move through the ETS (Chapter 12).
NTA tests whether students understand that ATP synthesis in photosynthesis relies on a proton gradient across thylakoid membranes, similar to the chemiosmotic mechanism in mitochondria. The key trap: students confuse the location of proton accumulation—in chloroplasts, protons accumulate INSIDE the thylakoid lumen, while in mitochondria they accumulate in the intermembrane space. Remember: in both organelles, the proton gradient drives ATP synthase, but the anatomical location differs due to different membrane structures. This concept bridges photosynthesis and respiration, making it highly testable for integrated understanding of cellular energy production.
What does NCERT say about Let us now try?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.