Autotroph

Plants are the most abundant and recognizable autotrophs on Earth. If you have noticed a houseplant on a windowsill imperceptibly turn its leaves toward the sun, you have probably guessed that plants are photoautotrophs. Plant leaves soak up the energy in sunlight and use it to make food. Plants take in water through their roots and atmospheric carbon dioxide through their leaves. Plant cells absorb light energy to fuel the synthesis of inorganic hydrogen, oxygen, and carbon into a sugar that nourishes them. This process is known as photosynthesis.

Because plants, as autotrophs, make living tissue solely out of nonliving material, they form the foundation of all food chains. Can you think of one thing you eat that does not, ultimately, come from plants? Plants are called primary producers because they create themselves out of transformed inorganic matter and, thus, are the "original food" that sustains all living things.