Biological Importance of Water

The Biological Importance Of Water Water plays a huge role in our lives, the molecule which is comprised of two atoms of hydrogen and one atom of oxygen bonded together has many complex properties. The molecule maintains a bent shape due to its tetrahedral arrangement and the negative lone pair of electrons on the oxygen. The electrons from both hydrogen and oxygen are joined covalently but the difference in electronegativity lets the electrons from hydrogen get pulled slightly toward the oxygen therefore making the hydrogen positive and the oxygen negative (a dipole molecule). Hence water being a polar molecule, the result of this lets water get attracted to other polar molecules and more importantly to other water molecules. Hydrogen bonds form in-between these polar molecules. The many unique properties water withholds will be discussed in this essay varying from its thermal properties to its solvent properties. The polar molecule attracts other polar water molecules. The slightly negative oxygen is attracted to the slightly positive hydrogen. Weak hydrogen bonds connect them. Electrons are pulled closer to oxygen making oxygen negative and hydrogen positive and therefore polarised. Solvent properties Since water is polarized it attracts ions and other polarized molecules. Water can collect around the molecule separate it making the chemicals able to move freely around and react with other chemicals. For example when NaCl enters water they dissociate into ions (Na+) and (Cl-), this occurs because both ions are more attracted to water dipoles. The water molecules surround the ions therefore making it hydrated, the molecules are bound providing a osmotic surface. This process takes place withen animals and plants. In order for a plant to abssorb minerals from the soil and for the blood(waterbased) to transport glucose, amino acids and minerals. Without this soloution living orgasisms wouldn’t be able to physical survie due to lack of nutrients. All metablic reactions happen in this soloution, such a respiration, excretion and photosythesis. In the circumstance that a molecules intermoleculer bonds are to strong the charged surface normally gets attracted to water which would then remain isolated, this therefore avoids them joining – collodical suspension. The plasma in your blood is a example of a collodical suspension as it carries all the nurtirents and elctrolytes but doesn’t fuse with the red blood cells. Thermal properties A realtively large proportion of energy is needed to increase the tempreture of water (high heat capacity) because of the large amounts of hydrogen bonds water pocesses. The more water content there is the harder it is to change the tempreture. Due to the high water content inside our bodies changing tempreture is a slow process, making maintaing a stable body tempreture easy, water acts as a buffer. This is obviously a advantage so enzymes can work at there optium tempreture. When sweating occurs a lot of heat energy escapes via evaperation making it a good cooling mechanism and helping organisms mantian the optium body tempreture which is vital to endothermic organisms. Density and freezing properties When water is solid , its less dense then it was when it was in liquid form. Ice floats because it is about 9% less dense than liquid water. The density of water starts to decrease after 4 celsus and therefore starts to float, insulating water particals below it. As water cools below 4Â °C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice. If it wasn’t for density being less dense water would sink and the whole ocean would freeze killing water life and reducing the circulate nutrients in oceans. When water freezes is expands inorder to make space for more hydrogen bonds. Water stays liquid through a large tempreture range which helps water animals live. High surface tension and cohesion Since water moves together in long unbroken columns through plants (xylem tissue)- the low viscosity allows water to drift easily. Transpiration steam occurs in soloution and is held together by cohesion. Water molecules attach to the xylem vessel showing the use of adhesion(because both water and cellulose are polar molecules there is a strong attraction for water within the hollow capillaries of the xylem). The guard cell is turgid because it has an increase in turgor pressure – water enters the central vacuole by osmosis. The cohesion of water molecules creates a large surface tenison ontop of the water letting small organisms use it as a habitat. Water also effects the support of mammals due to the waterfilled tissue which boosts are skeletal support. All of these properties show that water has great biological importance and is fundamentally vital for any living organisms to survive.