The leaf is the primary site of photosynthesis in plants.
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Image has been released into public domain (found on wikipedia.org).
Photosynthesis is the name of the process by which
water, carbon dioxide, and solar energy into sugars and oxygen.
It is a complex chemical process by which plants and other autotrophs create the energy needed for biological life. The equation above shows the production of CH2O (formaldehyde), only one of the many carbohydrates that actually form.
The oxygen that is a byproduct of the photosynthesis reaction leaves the plant through the stomata (openings between guard cells on the surface of a plant's epidermis that let in carbon dioxide and let out oxygen). This oxygen is essential in supporting life on Earth.
It is estimated that a full-grown, healthy maple tree has about 500 square feet of leaves weighing about 500 pounds. This represents a total chloroplast surface area of about 140 square miles. Believe it or not, a single maple tree can make two tons of sugar on one good sunny day! (The Way Life Works, Hoagland and Dodson) That's a lot of sugar!
Early bacteria converted solar energy by a different photosynthetic reaction, one which requires an anaerobic environment (one without oxygen), but which produces water as a waste product. The photosynthetic activity of this early bacteria was an interim step in building the oxygen content of Earth's early atmosphere.
The reverse process of photosynthesis is known as respiration. Respiration occurs in all organisms.
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