Step 4: Conduct an investigation and record your findings. - Pick a green leaf and boil it in a water bath over a Bunsen burner. - Take the leaf out of the water when it is soft and put it in a test tube containing some ethanol. - Put the test tube in a beaker containing some water at room temperature. - Heat up the water in the beaker until the ethanol starts to boil. \( \left(+/-78^{\circ} \mathrm{C}\right) \) When the leaf turns white take it out of the ethanol and soak the leaf in a beaker containing hot water. - When the leaf is soft again take it out of the water and spread it open on a ceramic tile. - Use a dropper to add a few drops of iodine solution onto the leaf. Observe what

This experiment is a classic demonstration of photosynthesis and the presence of starch in leaves. Here’s a detailed breakdown of the steps and the expected findings: ### Step-by-Step Investigation 1. **Boiling the Leaf:** - **Purpose:** The leaf is boiled to kill it and to soften its tissues, making it easier to extract pigments. - **Expected Outcome:** The leaf will become soft and pliable. 2. **Soaking in Ethanol:** - **Purpose:** Ethanol is used to remove chlorophyll and other pigments from the leaf. This step is crucial because chlorophyll can mask the presence of starch. - **Procedure:** Place the boiled leaf in a test tube with ethanol and heat it in a water bath until the ethanol boils. - **Expected Outcome:** The leaf will turn a whitish color as the chlorophyll is removed. 3. **Soaking in Hot Water:** - **Purpose:** This step is to soften the leaf again after it has been treated with ethanol. - **Expected Outcome:** The leaf will regain some softness, making it easier to spread out. 4. **Spreading the Leaf:** - **Purpose:** To prepare the leaf for the iodine test. - **Expected Outcome:** The leaf should be flat and open on the ceramic tile. 5. **Adding Iodine Solution:** - **Purpose:** Iodine solution is used to test for the presence of starch. When iodine comes into contact with starch, it turns a blue-black color. - **Procedure:** Use a dropper to add a few drops of iodine solution onto the leaf. - **Expected Outcome:** If starch is present in the leaf, the areas that were exposed to light during photosynthesis will turn blue-black, indicating the presence of starch. ### Conclusion - **Findings:** The experiment demonstrates that the green parts of the leaf (where photosynthesis occurs) contain starch, which is a product of photosynthesis. The areas that do not turn blue-black indicate that they did not undergo photosynthesis, likely due to lack of light exposure. ### Summary of Observations - The leaf turns white after being treated with ethanol, indicating the removal of chlorophyll. - The presence of blue-black coloration after adding iodine indicates the presence of starch, confirming that photosynthesis occurred in the green parts of the leaf. This experiment effectively illustrates the process of photosynthesis and the role of chlorophyll in starch production.