Water is a necessary and vital component for sustaining living organisms.
According to the PBS science documentary series, "Nova", the presence of water within the Earth's physical environment sustains the environment and the life that depends on it. Plants, animals and humans rely on the water in the atmosphere and in the environment, as well as what's in their bodies to maintain the basic functions of life. Not surprisingly, scientists in search of life on other planets check to see if there's water there first.
Water Components
The chemical makeup of water has a lot to do with why it's so essential to life in general, and plant, human and animal life in particular, according to the Royal Society of Chemistry website. The bonds that form an H2O molecule form through the joining of electron pairs belonging to hydrogen and oxygen. These are described as covalent bonds, which hold considerable strength. Water molecules also carry a polar charge where oxygen is negative and the hydrogen atoms are positive. This makes it easier for water molecules to mix with other compounds and also contributes to water's ability to hold together.
Function
Plant, human and animal metabolism processes rely on water as a solvent and as a transporter of nutrients and oxygen throughout the body, according to "Nova." Water's chemical structure makes it easy for most food materials to dissolve once inside the digestive system. According to the Royal Society of Chemistry, materials such as amino acids, sugars, proteins and nucleic acids can travel through the bloodstream because of water's ability to contain them. Once nutrients reach cellular structures, water assists with transporting materials in and out of cells.
Photosynthesis
Photosynthesis processes enable plants to manufacture the food they need to sustain life. To do this, plants convert the energy contained inside light into sugar using carbon dioxide and water as part of the process, according to Estrella Mountain Community College. In effect, the energy contained inside water's hydrogen bonds provides the fuel needed to carry out the conversion process. As light is absorbed, water molecules split apart, releasing the hydrogen atoms for use within the chemical interactions that produce food for the plant. As water is a key ingredient within photosynthesis, its importance is vital to plant health and growth.
Animal Metabolism
The chemical reactions that take place inside the body--be it animal or human--rely on water's physical and chemical make-up to facilitate metabolism processes. According to Kimball's Biology Pages website, the presence of water creates an osmotic effect that allows nutrients and waste materials to move in and out of cells. This osmotic effect--called osmosis--is based on a concentration, or pressure gradient that maintains a certain concentration of water inside and outside of cell structures. As water moves in and out of cell walls, it carries nutrient materials in and waste materials out.
Equilibrium
Liquid water is the only chemical material capable of maintaining its structure within a wide temperature range, as demonstrated by its freezing (32 degrees Fahrenheit) and boiling (212 degrees F) points, according to "Nova." This quality enables water to be a buffer, both inside plant, animal and human bodies, as well as within the Earth's environment and atmosphere, according to the Royal Society of Chemistry. This buffering effect maintains a certain equilibrium within the animal body that allows normal chemical reactions to continue when body temperatures rise.
Water also plays an essential role in maintaining equilibrium within plant structures by creating pressure effects within plant cells, stems and leaves, according to Florida State University. These effects enable plants to stand upright and conduct needed nutrients throughout the plant body.
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