water is essential to life
101digestive system, human — Introduction the system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract (alimentary canal), or the series of structures and organs through which food and liquids pass… …
102Netherlands, The — officially Kingdom of The Netherlands byname Holland Country, northwestern Europe. Area: 16,033 sq mi (41,526 sq km). Population (2002 est.): 16,142,000. Capital: Amsterdam; Seat of Government: The Hague. Most of the people are Dutch. Languages:… …
103Mars — /mahrz/, n. 1. the ancient Roman god of war and agriculture, identified with the Greek god Ares. 2. Astron. the planet fourth in order from the sun, having a diameter of 4222 miles (6794 km), a mean distance from the sun of 141.6 million miles… …
104Nitrogen — carbon ← nitrogen → oxygen ↑ N ↓ P …
105space exploration — Investigation of the universe beyond Earth s atmosphere by means of manned and unmanned spacecraft. Study of the use of rockets for spaceflight began early in the 20th century. Germany s research on rocket propulsion in the 1930s led to… …
106Survival skills — This article is about survival techniques. For the hip hop album by KRS One and Buckshot, see Survival Skills. Astronauts participate in tropical survival training at Albrook Air Force Base near the Panama Canal. From left to right are an… …
107Sustainability — Achieving sustainability will enable the Earth to continue supporting human life as we know it. Blue Marble NASA composite images: 2001 (left), 2002 (right). See also: Sustainable development Sustainability is the capacity to endure. For humans,… …
108chemical compound — Introduction any substance composed of identical molecules consisting of atoms (atom) of two or more chemical elements (chemical element). All the matter in the universe is composed of the atoms of more than 100 different chemical elements …
109Desert — Not to be confused with dessert. This article is about dry terrain. For the act of abandoning or withdrawing support, see desertion. For other uses, see Desert (disambiguation) …
110oxygen — oxygenic /ok si jen ik/, oxygenous /ok sij euh neuhs/, adj. oxygenicity /ok si jeuh nis i tee/, n. /ok si jeuhn/, n. Chem. a colorless, odorless, gaseous element constituting about one fifth of the volume of the atmosphere and present in a… …
