Photosynthesis is the process whereby green plants produce food and release oxygen. For this process to take place, plants need water, sunlight, carbon dioxide, chlorophyll and certain minerals. Take a healthy plant that has about a half dozen leaves. Cover each leaf with a piece of black plastic cut from a trash or lawn bag. Use tape to secure the bags to the leaves. Keep all other factors, such as the temperature and the amount of water the plant receives, the same. After several days, remove the plastic and observe any changes to the plant and it’s leaves from not receiving light.
Chlorophyll is a green substance that enables plants to make food using the photosynthesis process. Cut a section of leaf from a plant and place it in a test tube filled with alcohol. To safely heat the alcohol, which is flammable, fill a pot with water and bring it to a boil on a stove. Wearing an oven mitt, use a test tube holder to lower the test tube into the boiling water for 10 minutes. The alcohol will turn green as chlorophyll is extracted from the leaf.
Plants need light for photosynthesis to occur. Their leaves respond to external stimulus from light. This is called phototropism. Conduct an experiment to show how a plant’s leaves will seek light. Place a small plant in a vertically-standing shoe box. Cut a hole several inches in diameter on one side near the top of the box. Place the box so that sunlight hits the hole. Make daily observations to see if the plant’s leaves grow up toward the hole as they seek light.
Trees get the water they need through their roots in the ground, not from their leaves. In fact, water usually runs right off of leaves. Lay three books on their side and set one end of a ruler on the books to make a ramp. Position another ruler parallel to the first and 3 or 4 inches apart. Collect about 10 broad leaves and lay them down on top of the rulers, starting at the bottom and overlapping them as you go higher. This is similar to how shingles are installed on a roof. Press down slightly on the middle of the leaves (between the rulers) to form a slight trough. Place a few sheets of paper underneath the rulers. Place a cookie baking tray that has a lip around it at the bottom of the rulers to catch water. Slowly pour water down the center trough of the leaves to prevent water from spilling over the sides. Observe that the paper under the leaves stays dry.