Testing Leaves for starch with Year 7

Last week, our Year 7 science class explored one of the most fundamental processes of life on Earth: Photosynthesis. To bring this topic to life, we conducted a fascinating lab experiment to explore the role of light in photosynthesis and test leaves for the presence of starch, a product of this vital process.

Problem question was simple: Is light an essential requirement for photosynthesis?

Students answered this question by checking for starch in leaves exposed to light and those kept in the dark.

Specifically students selected two leaves: one from a plant that had been in the sunlight and another from a plant kept in the dark for 3 days. Each leaf was boiled in water to soften it and then in alcohol to remove chlorophyll, leaving them pale and ready for testing. Finally they immersed the leaves in iodine solution. The exciting moment came as the iodine reacted with starch, turning blue-black in areas where starch was present.

This experiment clearly demonstrated that light is essential for photosynthesis to occur, as it drives the production of glucose, which plants convert into starch for energy storage and students were excited to see theory come alive in the lab. Their enthusiasm made this experiment a truly rewarding experience for all involved!