Brief Summary
This lesson recaps previous experiments demonstrating the necessity of carbon dioxide, water, and light for photosynthesis. It then details two new experiments: one proving light's essential role in starch production within leaves, and another demonstrating oxygen's release during photosynthesis using the hydrilla plant.
- Light is essential for photosynthesis and starch production.
- Oxygen is released during the photosynthesis process.
- Experiments are important for understanding and examination purposes.
Recap of Previous Lessons
The lesson begins by recalling previous experiments related to photosynthesis. These include the photosynthesis equation, Bruce Lee's experiment, demonstrating carbon dioxide's necessity for photosynthesis, and experiments highlighting the importance of water and light for the process.
Experiment: Light's Role in Starch Production
To demonstrate that light is a vital factor for photosynthesis, a potted plant is used. The leaves are destarched by keeping the plant in a dark room for two to three days. A portion of a leaf is then covered with black paper, and the plant is placed in sunlight for two to four hours. After this period, the leaf is tested with iodine. The part of the leaf exposed to light turns blue-black, indicating the presence of starch, while the covered part does not, proving that light is essential for starch production during photosynthesis.
Experiment: Oxygen Liberation During Photosynthesis
This experiment aims to prove that oxygen is released during photosynthesis, also known as the hydrilla experiment. A beaker is filled with water, and hydrilla plant pieces are placed inside. A funnel is inverted over the plant, and a test tube filled with water is inverted over the funnel's stem. The setup is placed in sunlight for two to four hours. Fine bubbles are observed coming from the hydrilla and collecting in the test tube. Once enough gas has collected, a glowing splint is inserted into the test tube, and it relights, confirming the presence of oxygen.
Conclusion
The lesson concludes by summarising the experiments conducted, which align with the photosynthesis equation. These experiments, including the starch formation test with iodine and the oxygen liberation demonstration, are highlighted as essential for understanding photosynthesis and are important from an examination perspective.
