How Plants Find Food
Plants generally rely on soil for physical support and water absorption, but they also draw important nutrients from soil—mainly nitrogen, phosphorus, potassium, magnesium, and other elemental nutrients. A plant’s roots—and especially the tiny root hairs which protrude from them—are the most essential organ for the absorption of nutrients. They tend to grow quickly when searching for nutrients in soil, and slow down upon finding them to focus of absorption—a "behavior" somewhat analogous to foraging animals who tend to linger in food-rich areas.
What is Photosynthesis
Most of the solid material in a plant is taken from the atmosphere. Through a process known as photosynthesis, plants use the energy in sunlight, plus water, to convert atmospheric carbon dioxide into simple sugars, which are then used as building blocks to form the physical structure of the plant. Also essential to this process is chlorophyll--a green, magnesium-containing pigment which is mainly found in plant leaves, which gives them their color. Plants are generally quite adept at orienting themselves to maximize their exposure to the sun and rainfall.
The Importance of Photosynthesis
It is difficult to overstate the importance of the photosynthetic process; it is the primary equation of all life on the planet. A byproduct of photosynthesis is atmospheric oxygen, the most basic element necessary to support earth’s animal life. Photosynthesis is also the source of the carbon in all the organic compounds within all organisms' bodies. The average global solar energy capture by photosynthesis is approximately six times larger than current power consumption of human civilization.