Nutrition

Nutrition is the means by which organisms obtain and use nutrients. Nutrition is also the determination of the kinds and quantities of substances (nutrients) needed by organisms to sustain life. Some organisms, such as plants, require only a supply of light, water, and a few other molecules and ions in order to thrive, and they are known as autotrophs, or self-nourishers, for they literally build their own molecules and capture energy in the process. There are a few other non-plant autotrophic organisms in the deep oceans near geothermal vents that are able to build their own nutrients without using sunlight.

Although green plants get the energy they need directly from sunlight, animals must get the energy that they need for...