hydrogen cycle
71sun — sunlike, adj. /sun/, n., v., sunned, sunning. n. 1. (often cap.) the star that is the central body of the solar system, around which the planets revolve and from which they receive light and heat: its mean distance from the earth is about 93… …
72Internal combustion engine — The internal combustion engine is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal combustion engine, the expansion of the high temperature and high …
73cell — cell1 cell like, adj. /sel/, n. 1. a small room, as in a convent or prison. 2. any of various small compartments or bounded areas forming part of a whole. 3. a small group acting as a unit within a larger organization: a local cell of the… …
74atmosphere, 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… …
75hydrosphere — /huy dreuh sfear /, n. the water on or surrounding the surface of the globe, including the water of the oceans and the water in the atmosphere. [1885 90; HYDRO 1 + SPHERE] * * * Discontinuous layer of water at or near the Earth s surface. It… …
76photosynthesis — photosynthetic /foh teuh sin thet ik/, adj. photosynthetically, adv. /foh teuh sin theuh sis/, n. Biol., Biochem. (esp. in plants) the synthesis of complex organic materials, esp. carbohydrates, from carbon dioxide, water, and inorganic salts,… …
77chemical element — Introduction also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed. This article considers the… …
78Sun — This article is about the star. For other uses, see Sun (disambiguation). The Sun …
79Fusion power — The Sun is a natural fusion reactor. Fusion power is the power generated by nuclear fusion processes. In fusion reactions two light atomic nuclei fuse together to form a heavier nucleus (in contrast with fission power). In doing so they release a …
80Microbial metabolism — is the means by which a microbe obtains the energy and nutrients (e.g. carbon) it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic… …
