Water (H20) is the planet’s most abundant compound (Brown, 1998) and a major component in all living things (Brooker et al. 2010; Sharp, 2001). Water has anomalous physical and chemical properties; these properties are biologically relevant, some of them are necessary for life as well as determine the size, shape and function of living organisms (Brooker et al. 2010; Sharp, 2001). Water is a polar molecule in that it has positive and negatively charged areas; two positive hydrogen atoms and one negative oxygen atom. Hydrogen bonds are formed between hydrogen and oxygen atoms leading a stable collective structure that allows water to be in liquid form across a temperature range of 0-1000C. This liquid state is important for living organisms (Brown 1998).
One of the most important biological functions of water is as a solvent; it dissolves important molecules such as sugars, salts, metabolites and larger molecules such as nucleic acids and proteins. Water enables molecules such as proteins, membranes and nucleic acids to adopt their functional structures through differential solubility (Brown 1998; Sharp, 2011). As a result of its solvent ability, water has an important role in transport of molecules. For instance, water-based transport occurs in plant uptake of minerals, digestion of food, movement of amino acids and sugars and all transport in the cytoplasm, plasma, blood and tissue fluid. Water’s low viscosity enables it to move easily through tubes and transport vessels.
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"How is Water a Necessity for Life?".
Water is an ideal environment within which chemical reactions occur because of its solvent properties and thermal stability (Brown, 1998; Sharp, 2001); enzyme reactions such as respiration, photosynthesis and excretion all occur in solution. Water’s ease of solvation enables the acid-base reactions that constantly occur in biological systems such as enzyme catalysis, ion channel reactions, protein folding, communication of signals, and bioenergetics pathways (Sharp, 2001).
Water also plays an important role in heat transfer and thermoregulation. Its high heat capacity allows it to act as a buffer allowing endothermic organisms to maintain the constant body temperature that is necessary for enzyme activity and regulation of metabolism (Brown, 1998; Sharp, 2001). Water is important for reproduction; it enables the movement of the sex gametes towards each other, provides a medium in which the fetus develops as well as thermal stability. In plants, water enables the turgidity that is needed for maintaining a maximum leaf area to promote light absorption and photosynthesis. In animals, water in the tissues is important for support. Some plants and animals rely on water for movement; nastic movement in plants such as opening of flowers and aquatic movement in animals, respectively (Brown, 1998)
In conclusion, water is a major component of all biological organisms and plays roles that are essential to life. Its functions in both plants to animals include transport of essential nutrients and materials, thermoregulation, reproduction, essential chemical processes, metabolism, and support. In the absence of water, most living things cannot thrive. Water is essential to all living organisms.
- Brooker, Widmaier, Graham, and Stiling. (2010). Principles of Biology.
- Brown, C (1998). The biological importance of water. Bio Factsheet, No. 30. Curriculum Press, ISSN 1351-5136. Retrieved 28 August 2014 from http://papers.xtremepapers.com/
- Sharp, K. (2001). Water: Structure and Properties. Encyclopedia of Life Sciences. Retrieved 28 August 2014 from http://crystal.med.upenn.edu/
