31/07/2026
📌 Slide 1 – Aim
🌿 Every experiment begins with a question.
Today’s practical will help you test the presence of starch in a leaf using iodine solution and understand how it proves photosynthesis.
Save this series for your practical exams!
📌 Slide 2 – Boil the Leaf in Water
💧 First step done!
Boiling the leaf in water kills the cells, stops metabolic activities and prepares the leaf for the starch test.
Understanding why each step is performed is just as important as remembering it.
📌 Slide 3 – Boil in Alcohol
🧪 Safety first!
The leaf is heated in alcohol using a water bath, never directly over a flame. Alcohol removes chlorophyll so the iodine colour change becomes clearly visible.
📌 Slide 4 – Wash the Leaf
🚿 A simple step with an important purpose.
After removing chlorophyll, the leaf becomes brittle. Washing it in warm water softens the leaf and removes the alcohol.
📌 Slide 5 – Add Iodine
🟤➡️🔵 The moment of truth!
Add a few drops of iodine solution. This reagent helps detect whether starch is present in the leaf.
Watch closely… the observation is coming next!
📌 Slide 6 – Observation
💙 Observation matters more than memorisation.
If the leaf turns blue-black, starch is present.
Always record observations carefully during practical examinations.
📌 Slide 7 – Conclusion
✅ Conclusion
The blue-black colour confirms the presence of starch.
This proves that photosynthesis has occurred in the green leaf.
If this series helped you understand the experiment, share it with a friend preparing for Biology practicals!
