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Activity 5.3 — CO₂ & Photosynthesis (KOH)
NCERT Activity 5.3: Two plants under bell jars — one with KOH (absorbs CO₂), one without. The plant without CO₂ cannot photosynthesize, proving CO₂ is essential.
How To Perform
1
Set Up Experiment
Place KOH in one bell jar, water in the other. Seal both plants.
2
Expose to Sunlight
Let both plants sit in sunlight for several hours.
3
Iodine Test
Test leaves from both plants with iodine solution.
4
Conclude
No CO₂ = no starch. CO₂ is essential for photosynthesis.
⚠️ Safety Notes
- •KOH (potassium hydroxide) is caustic — it can cause skin burns. Wear gloves and goggles.
- •Handle bell jars carefully — they are made of glass and can break.
- •Alcohol used for decolorization is flammable — use a water bath.