Source of Oxygen in Photosynthesis — NEET Biology
📚 Practice ConceptIn green plants H₂O is the hydrogen donor and is oxidised to O₂. Some organisms do not release O₂ during photosynthesis. When H₂S, instead is the hydrogen donor for purple and green sulphur bacteria, the 'oxidation' product is sulphur or sulphate depending on the organism and not O₂. Hence, he inferred that the O₂ evolved by the green plant comes from H₂O, not from carbon dioxide. This was later proved by using radioisotopic techniques. The correct equation, that would represent the overall process of photosynthesis is therefore:
Choose the correct sequence of discoveries: A. Role of chlorophyll B. Oxygen comes from H₂O C. Sunlight is essential D. Starch formation as evidence
View solution & NCERT explanation
Correct answer: B — D → C → A → B
Starch formation (Sachs) → Sunlight essential (Ingenhousz) → Role of chlorophyll (Sachs) → Oxygen from H₂O (van Niel).
What does NCERT say about green plants HO hydrogen?
Has this concept appeared in NEET?
Which chapter is this from?
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.