humans are highly adaptable and have adapted to obtaining food in many different ecosystems. humans generally use cooking to prepare food for consumption. the majority of the food energy required is supplied by the industrial food industry
which produces food through intensive agriculture and distributes it through complex food processing and food distribution systems. this system of conventional agriculture relies heavily on fossil fuels
which means that the food and agricultural systems are one of the major contributors to climate change
food is any substance consumed to provide nutritional support and energy to an organism.[2][3] it can be raw
and some microorganisms use photosynthesis to make some of their own nutrients.[5] water is found in many foods and has been defined as food by itself.[6] water and fiber have low energy densities
while fat is the most energy-dense component.[3] some inorganic (non-food) elements are also essential for plant and animal functioning.[7]
either by related content or by how it is processed.[8] the number and composition of food groups can vary. most systems include four basic groups that describe their origin and relative nutritional function: vegetables and fruit
and sugar-sweetened beverages.[10][11][12] the food and agriculture organization and world health organization use a system with nineteen food classifications: cereals
food forms a web of interlocking chains with primary producers at the bottom and apex predators at the top.[14] other aspects of the web include detrovores (that eat detritis) and decomposers (that break down dead organisms).[14] primary producers include algae
bacteria and protists that acquire their energy from sunlight.[15] primary consumers are the herbivores that consume the plants
the animals that have no known predators in its ecosystem.[17] humans are considered apex predators.[18]
mushrooms and seaweed.[16] cereal grain is a staple food that provides more food energy worldwide than any other type of crop.[19] corn (maize)
and rice account for 87% of all grain production worldwide.[20][21][22] just over half of the world's crops are used to feed humans (55 percent)
with 36 percent grown as animal feed and 9 percent for biofuels.[23] fungi and bacteria are also used in the preparation of fermented foods like bread
energy from the sun is absorbed and used to transform water and carbon dioxide in the air or soil into oxygen and glucose. the oxygen is then released
[26][27] making photosynthesis the primary source of energy and food for nearly all life on earth.[28]
oxygen and hydrogen are absorbed from the air or water and are the basic nutrients needed for plant survival.[30] the three main nutrients absorbed from the soil for plant growth are nitrogen
bacteria and other microorganisms also form the lower rungs of the food chain. they obtain their energy from photosynthesis or by breaking down dead organisms
waste or chemical compounds. some form symbiotic relationships with other organisms to obtain their nutrients.[31] bacteria provide a source of food for protozoa
[32] who in turn provide a source of food for other organisms such as small invertebrates.[33] other organisms that feed on bacteria include nematodes
protozoa and microscopic fungi)[34] provide a crucial source of food to many small and large aquatic organisms.
life would scarcely exist because bacteria convert atmospheric nitrogen into nutritious ammonia. ammonia is the precursor to proteins
pepper and eggplant or seeds like peas commonly considered vegetables.[37] food is a fruit if the part eaten is derived from the reproductive tissue
seeds and fruits used as vegetables are removed.[40] grains can be defined as seeds that humans eat or harvest
rye