Why Is Water So Important To Life?

Nisha Kanabar Biology 11/ 11/04

WHY IS WATER SO IMPORTANT TO LIFE?

Water is one of the most crucial yet common substances on our planet. It comprises over 70% of the earth’s surface; Water is everywhere, including the air we breathe. Without it, there would literally be no life. Every single living thing contains water. The element of water is itself so significant that it justifies particular importance. The first components of life are actually thought to have originated from primordial waters. Ever since the beginning, water has been influencing the maintenance of the earth, including the shape – how do you think the world’s continents became the figures they are today? Water even helps the earth’s climate from becoming excessively hot or cold. While the lands absorb and release heat from the sun much too quickly, the oceans absorb and release slowly. This makes the breezes caused by the ocean make the weather suitable – warm in the winter, and cool in the summer. Unsurprisingly, where water goes, civilization follows. The several great nations today have been upholding due to this sole element. Presently, water demand is progressively high. As development increases, so does water necessity. Even though we do live in a water-based world, 97% of it is situated in the oceans, which is why water-purifying technology is emerging so rapidly. We now know the importance of water generally. Some basic, obvious reasons as to why water is so essential to life.

As mentioned briefly, one of the prime reasons water is so important is its role in living organisms. Your body itself consists of 65% water, as does a mouse. An elephant, or an ear of corn, on the other hand has 70% water. Every living thing uses water to help its life processes, and helps nutrients spread throughout its body. Water assists the body to even turn nutrients into energy, and influence the process in which the organism repairs or expands itself. Every living thing must have a balanced water supply, or effects may be fatal. Even though a human being is able to live for about 2 months without food, it cannot live without water for even a week. Water is also used in our day to day life. Even though we don’t realize, we use water for cleaning, cooking, bathing, and getting rid of waste. Water use of this sort is in many areas (particularly Africa, Asia and South Africa) is known as a luxury. For agriculturally based homes, water is also needed for crop irrigation as well. In various countries, hydroelectricity is people’s only means of power. This is another major use for water, as these power stations create electricity through the energy of falling water from waterfalls and dams. One major water purpose is its role in nature as its states of matter - solid, liquid and gas. It forms many different figures on earth, for example: clouds in the sky, waves and icebergs in the sea etc. Here, even though I have only named a few, each state of matter is already mentioned. Clouds – gas, waves – liquid, and icebergs – solid. Without water, these aspects of the natural world and environment would be unimaginable.

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The evident importance for water is clear. However, the features underlying these basic elements are the properties of water – the molecule H20 – which are the fundamental reasons to why water itself is so biologically important to life. The first quality of water is its transparency. Transparency of water is related to how deep the light will penetrate through the water, thus, the travel of light into water is extremely essential in order for any life to develop, as the sun is the main source of energy for any biological occurrence. The sun’s light instigates photosynthesis; a crucial plant process that produces food and oxygen that the plant needs to grow. Therefore, for the sun’s rays to pierce through the water’s surface and maintain underwater life, the water must have transparency. Though it is ultimately colourless, once light rays bounce through, they transform into various hues and therefore tint the sea its natural blue-green colour.

An imperative attribute of water is its polarity. Because the nucleus of the oxygen atom is more dominating than the two small hydrogen atoms, this bond inequality gives the hydrogen atoms (to the left - H2 and H3) partial positive charges, while the oxygen atom (H1) gains negative charges. This makes the water molecule polar which influences the basis of many other water properties. The polarity of water also explains why the substance is at a liquid state at regular temperature and pressure. The polarity of atoms causes molecules to be attracted to each other (positive➔negative and vice versa). This is called Hydrogen Bonding.

Hydrogen bonding is quite weak in comparison to regular molecular covalent bonds; however it is responsible for many physical properties of water. Though the bonds between the molecules are loose, they are the strongest when arranged up through the axis of O-H bonds in adjoining links of water molecules. The linkages in ice however have molecules arranged in lattice-like form. Despite this, the randomness of the hydrogen bond link proves to be denser than the structured ice bond. Thus simply, this is why ice floats on water. This means that water expands as it freezes (while most other substances shrink when solidified). Water is most dense at 4°C, which has significant relevance towards lakes and other still water in the winter. When water generally cools on the surface, the cold water (being denser) will sink. However interestingly, beyond the temperature of 4°C, the water on the surface (instead of becoming denser) becomes less dense. This lets it remain at surface level, thus forming ice.

Because water has good polarity, it is categorized as a solvent. This means that it is capable of dissolving several other substances, such as protein, salts and sugars. The main reason for this is that water molecules can easily form bonds with the molecules of other substances, thus dissolving it. If an ionic or polar compound were to be dropped into an area of water, the water molecules (being relatively small) would cluster around the compound, forming hydrogen bonds with them, once again having converse attraction links (+ and -). However, if the substance were non-polar (such as oil or fats) the molecules would stick to their own kind and resist bonding. Solvent properties of water are important biologically as several biochemical reactions are based within these certain solutions (such as reactions in the cytoplasm and blood).

Thermal properties of water are other means of importance. Firstly, there’s the Latent heat of the water. Latent heat is known as the energy that is implicated throughout the phase change of water. It is the heat gained by water molecules while water evaporates. The heat added to evaporate the water is generally used to separate the hydrogen bonds between molecules yet at the same time not increase the temperature of the body of water. This heat is then stored inside the evaporating water molecules and only released during condensation. Latent heat energy release is particularly important to control hurricanes or threatening cumulus clouds. Specific heat is another thermal aspect of water. Because water has a fairly high specific heat, it is more able to stabilize temperature. Specific heat can be described as “the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1º C”. Water’s specific heat, at 1.00 cal/g °C, is unusually high, especially compared with other substances’. Because of this, water changes temperature less frequently when there’s an absorption or loss in the amount of heat. In fact, specific heat can also be traced back to hydrogen bonding. To break hydrogen bonds, heat must be absorbed, and to form bonds, heat must be lost. And how is the high specific heat of water greatly significant? This is where “water and maintenance of the earth’s climate” appears. Water can absorb and store heat, so at night or when it is cool a body of water is able to radiate warmth. It also makes the earth liveable through temperature.

Last but not least, another aspect in which water is important to life is Cohesion. Once again this property is based on hydrogen bonding. Liquid water has high cohesion due to the interconnections of strong hydrogen bonds. High cohesion means that the molecules have a tendency to stick together. Thus, cohesion along the surface area of a lake or pond creates surface tension. This makes the surface water slightly more inseparable and consequently denser. This allows certain objects to float across the surface of water, such as leaves, certain insects etc. Though it may not seem to be, this is also quite vital for life to function. Example, when water needs to travel up the xylem through the stems of plants, the intermolecular attraction is able to keep the travelling procession of water together. With another substance with another surface tension, this would not be able to occur.

Though it is most obvious that water is a vital element to life, we rarely knew why. We were aware of the basic, common-knowledge material. But did we really know how scientists came about to bring the common-knowledge material? This is what this composition consisted of: The underlying biological truth about the importance of water. In more ways than we can imagine, water is affecting our lives greatly. We have discovered several properties of water’s significance: Transparency – for life to grow underwater, Polarity and Hydrogen Bonding – important structure of the molecule that provide the basics, Solvent properties – helping biochemical reactions within the body, Thermal properties – controlling the weather and Cohesion – assisting the development of plants and such. Initially, you may not have truly been convinced of the statement “Without water there would be no life”. How about now? Now that you are technically aware, don’t you feel a little more value towards the substance that there would be no existence without?

BIOLOGY