A tree breathes through its leaves using chlorophyll, the substance that makes leaves green. Chlorophyll absorbs the carbon dioxide in the air and uses it alongside water to break down minerals absorbed through the tree'... More »

In dry air that does not contain pollution, the predominant gas is nitrogen, which makes up 78 percent of the atmosphere. The next two most voluminous gases are oxygen (21 percent) and argon (1 percent). Other gases appe... More »

Trees need leaves primarily because of photosynthesis and respiration. Photosynthesis is the process by which carbon dioxide is converted into nutrients that are needed by plants for survival. More »

Plant leaves contain chloroplasts, which have chlorophyll that absorbs light energy from the sun. Chlorophyll is the green pigment that is important for the process of photosynthesis in plants. More »

When the abscission layer of a plant grows, it cuts off the circulation of nutrients, sugar and water to the leaves, which causes the chlorophyll that gives the plant its green color to disintegrate and makes carotene sh... More »

Plants produce food in their leaves through photosynthesis, a process that uses chlorophyll to synthesize sustenance through carbon dioxide, sunlight, water and mineral-related nutrients. Chemical energy from photosynthe... More »

Leaves turn brown in autumn due to the deterioration of chlorophyll, the green pigment found in all leaves responsible for absorbing light for photosynthesis, explains the U.S. Forest Service. Intrinsically, the trees ar... More »