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Noun ( 1. (chemistry) A chemical substance, with chemical formula H2O, that is clear, colorless, oderless, and tasteless liquid that may also occur in various forms such as gas (water vapour) and solid (ice). Water is regarded as the universal solvent primarily due to its chemical and physical properties. It is one of the substances essential to life. Biomolecules (DNA, proteins, polysaccharides, etc.) are dissolved in water. It is also one of the requirements for photosynthesis. Some of its properties are described as follows: Water is a tasteless, odorless liquid at ambient temperature and pressure. Water is transparent, making it possible for aquatic plants to live in since sunlight can penetrate through. Water is a liquid under standard conditions. Water is polar molecule due to its oxygen that has a slight negative charge while its hydrogens have slight positive charge. Water molecules stick to one another by hydrogen bond. Water has high surface tension. It is essential to yield elasticity that drives the capillary waves. Water has high adhesion properties. Water has the ability for capillary action, the tendency to move up a narrow tube against gravity, a property relied upon by vascular plants, such as trees. Water has the second highest specific heat capacity (after ammonia) and high heat of vaporization. These properties allow water to regulate the Earth’s climate. Water is less dense upon freezing, causing the...

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Wolffian duct

1. One of a pair of tubes that carry urine from primitive or embryonic kidneys to the exterior or to a primitive bladder. In amphibians the reproductive system encroaches on the Wolffian duct; in some species the duct carries both urine and sperm, but most amphibians develop a separate tube to carry urine from the kidney. ( 2. The duct of the mesonephros that persists in the female chiefly as part of a vestigial organ and in the male as the duct system leaving the testis and including the epididymis, vas deferens, seminal vesicle, and ejaculatory duct. ( 3. A paired organ found in mammals including humans during embryogenesis. ( Syn: archinephric duct, Leydig’s duct, nephric duct, mesonephric...

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Wormian bones

1. Extra bone pieces that occur within a suture in the cranium. ( 2. Any of the tiny soft bones found in the sutures between cranial bones. ( Syn: intra sutural bones, sutural...

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