CO₂ Requirement in Photosynthesis — NEET Biology
📚 Practice ConceptAnother experiment you may have carried out where a part of a leaf is enclosed in a test tube containing some KOH soaked cotton (which absorbs CO₂), while the other half is exposed to air. The setup is then placed in light for some time. On testing for the presence of starch later in the two parts of the leaf, you must have found that the exposed part of the leaf tested positive for starch while the portion that was in the tube, tested negative. This showed that CO₂ was required for photosynthesis. Can you explain how this conclusion could be drawn?
How did the use of KOH in a test tube prove the necessity of CO₂ in photosynthesis?
View solution & NCERT explanation
Correct answer: A — KOH absorbs CO₂, preventing starch formation in that part
KOH absorbs CO₂, and absence of starch in that region confirms the requirement of CO₂.
What does NCERT say about Another experiment you may?
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.