oxygen sustains life processes
1Extraterrestrial life — For fiction, see Extraterrestrials in fiction. For other uses, see Alien (disambiguation). A 1967 Soviet Union 16 kopeks postage stamp, depicting a satellite from an imagined extraterrestrial civilization …
2Gaia hypothesis — The study of planetary habitability is partly based upon extrapolation from knowledge of the Earth s conditions, as the Earth is the only planet currently known to harbour life. The Gaia hypothesis, also known as Gaia theory or Gaia principle,… …
3Ecology — For other uses, see Ecology (disambiguation). Ecology …
4earth — /errth/, n. 1. (often cap.) the planet third in order from the sun, having an equatorial diameter of 7926 mi. (12,755 km) and a polar diameter of 7900 mi. (12,714 km), a mean distance from the sun of 92.9 million mi. (149.6 million km), and a… …
5community ecology — Introduction study of the organization and functioning of communities (community), which are assemblages of interacting populations of the species living within a particular area or habitat. As populations of species interact with one …
6Breathing gas — is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas. Other artificial gases, either pure gases or mixtures of gases, are used in breathing equipment and enclosed… …
7Solar energy — is the light and radiant heat from the Sun that powers Earth s climate and weather and sustains life. Since ancient times it has been harnessed for human use through a range of technologies. Solar radiation along with secondary solar resources… …
8feed — feedable, adj. /feed/, v., fed, feeding, n. v.t. 1. to give food to; supply with nourishment: to feed a child. 2. to yield or serve as food for: This land has fed 10 generations. 3. to provide as food. 4. to furnish for consumption. 5. to… …
9atmosphere, evolution of — Introduction the development of Earth s (Earth) atmosphere across geologic time. The process by which the current atmosphere arose from earlier conditions is complex; however, evidence related to the evolution of Earth s atmosphere, though… …
10human disease — Introduction an impairment of the normal state of a human being that interrupts or modifies its vital functions. health versus disease Before human disease can be discussed, the meanings of the terms health, physical fitness, illness …
