Starch Test in Leaves (Photosynthesis Proof)

Demonstrate that starch is produced in leaves during photosynthesis by testing for starch presence using iodine.

What you need

• A healthy green leaf (preferably from a plant left in sunlight)
• Beaker or metal pan
• Water
• Alcohol (ethanol or rubbing alcohol)
• Iodine solution (from a pharmacy)
• Test tube
• Stove or hot water bath (used with adult supervision)
• Forceps or tongs

How it works

If the leaf turns blue-black, it indicates the presence of starch, which confirms that photosynthesis has occurred. This is one of the most classical biology experiments.