The cytoplasm of a cell is a complex mixture of water soluble molecules. However some molecules, mainly the lipids, are unable to dissolve in water. The partial attraction and repulsion of the phospholipids to and from water causes them to form interfaces, or membranes, which separates the cytoplasm from the external environment.
Water also maintains relatively constant temperatures; this is because water has a specific heat capacity, which means it requires a lot of heat to rise or lower its temperature. This property is important to living organisms, because it means that sudden changes in temperature which could change the metabolic activity are avoided.
It also protects the cell from thermal damage. Waste heat generated from metabolic reactions would soon denature the cellular enzymes. The high specific heat capacity and high thermal conductivity of water in the cytoplasm drives away heat from cellular reactions. They have a high latent heat of vaporization: This means that when they warm up, some of the molecules gain sufficient energy to detach from the liquid and become vapour. Atoms require a considerable amount of energy, due to the need to break the hydrogen bonds between each molecule. As water evaporates it carries with it relatively large amounts of heat energy, cooling the surface that from which it vaporized from. The cooling effect of the sweating response of mammalian thermoregulation only works when it evaporates not, when it drips as sweat. Therefore panting is another mechanism of evaporative cooling.
They show strange properties as it cools. It has a maximum density, not as a solid like most molecules, but as a liquid at 4ºC. This causes ice to float, benefiting living organisms by forming an insulating layer on the surface of freezing ponds and lakes. This is especially important in cold climates and where there are cold seasons. Freezing can, however, also cause some damage to organisms exposed to a sub-zero temperature, this is because water expands when it freezes and it therefore would do so in cells. A lot of polar ectothermic species have 'anti-freeze' compounds like glycerol which prevent body fluids freezing even at temperatures below zero.
This liquid is also is needed during osmosis to balance the concentration gradients on two sides of a cell. Osmosis is the diffusion of water molecule down the concentration gradient. It is used in osmoregulation to control the levels of water in the human in the kidneys, if water potential is high in one area and low in another it will determine the movement of water in or out of the cell.
Water protects organisms from diseases. It is used to make mucus which filters the air we breathe in, preventing dusts and other unhealthy substances from entering our lungs.
Water is used to make synovial fluid which is used in lubrication. The synovial fluid which is used as lubrication to stops the bones from grinding away.
Gaseous exchange is even controlled by water, which is taking place in the leaves of a plant. For example, it is taken in through the roots when there is a high level of oxygen and low levels of carbon dioxide in the cell. Next it is taken up through the roots and taken to the guard cells making them turgid to allow the stoma to open up and exchange gases.
Hydrogen bonds between water molecules are responsible for the cohesive and adhesive properties of water. Cohesion means to 'like to stick to like' so in this case water sticks to water, and so water has high surface tension. The skin or thin first layer of large surfaces of water provides a habitat for small vertebrates, such as bond skaters, which glide across the water without penetrating the surface. Adhesion means a tendency to stick to different molecules, and in case of water to other polar molecules. This adhesion property of water causes capillarity, the ability of water to resist gravitational pull and rise up thin tubes, or form thin layers around soil particles. Adhesion and cohesion are particularly important as they allow water to follow up through the xylem tube and so play a big part in helping the transpiration stream takes place.
Another property of water is its transparency to visible light. Light can penetrate water to a considerable depth, as long as the water hasn't got tiny matter in suspense. Different wavelengths of light penetrate to different depths. Red and yellow light only travel to a maximum of 50 meters depth, whilst blue and violet light may reach 100 meters. This allows large volumes of water to serve as habitats for photosynthetic organisms. In germination water is also needed to allow seeds to develop and grow. It helps to provide it with the optimum environment.
Water is used as a transport route for all substances. Not only is it used for us to sail our boats on but is also used to carry nutrients in the plants across the phloem. The nutrients that are produced during photosynthesis are diluted into the water that is taken in up the roots and is passed on to other parts of the plant via the phloem. It also used in migration where water in the ocean is used to help migrate animals. When the temperature changes in the ocean, animals such as whales migrate from the colder regions to warmer regions where temperature is more appropriate for them to live in.
Another transportation route using water is the dispersal of seeds. Seeds fall from the parenting plant and subsequent dispersal by tidal water to other regions.
An additional mode of water is used to transport substances in the blood in the red blood cells.
Male gametes swim through the water to female gametes during external fertilisation.
Water is an important reagent in metabolic reactions, particularly in hydrolysis, and as a source of hydrogen in photosynthesis. Water is a key factor for hydrolysis to take place. It breaks hydrogen binds. Hydrolysis is used in digestion to break up carbohydrates and fats.
From this essay we can learn that a water molecule is dipolar and covalently bonded between oxygen and hydrogen. Due to this polarity water can form hydrogen bonds, and when it bonds with other polar atoms the new molecule becomes a soluble.
One of the properties of water is that it has high latent heat vaporization and when it cools it causes the solid form to float, acting as a good insulator.
Another factor is that it helps to balance the concentration gradient of many substances, whether that is liquid or gas.
A further point is that can be used in a mode of transport for most organisms.
Finally, it is really impossible to imagine life without water. One has only to survey the vast deserts of the Sahara! Before knowing what life is in a draught or waterless situation. The properties of this molecule make it so essential for life on earth, and so it is each and every person's responsibility to make sure it stays clean and available.
