Photosynthesis is the process by which green plants convert carbon dioxide and water into
glucose using sunlight energy absorbed by chlorophyll in chloroplasts. The equation for
photosynthesis is 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Photosynthesis occurs in two stages: lightdependent and light-independent reactions, which work together to convert light energy into
chemical energy stored in glucose, with oxygen released as a by-product. In this experiment, a
green leaf was tested for the presence of starch, which indicates photosynthesis had taken
place. First, the leaf was dipped in boiling water to kill it, stop all chemical reactions, and soften
the tissues, allowing alcohol to penetrate. It was then placed in hot alcohol (ethanol) to remove
the chlorophyll; before adding the leaf, the alcohol was clear and colorless, but afterward, it
turned green as chlorophyll was extracted. The texture of the leaf was firm and crisp before
being placed in alcohol and became brittle and fragile after. Removing the chlorophyll made the
leaf pale, improving visibility when iodine solution was added. The iodine solution reacted with
any starch present, turning blue-black, indicating that photosynthesis had occurred and glucose
was converted and stored as starch